I've also posted more regarding understanding the psychology of the Plymouth Brethren/Kerala Brethren in another post ("Understanding the psychology of the Plymouth Brethren/Kerala Brethren").
I'm quoting King from the above link:
"The Antinomians and Plymouth Brethren of England and America have for a long while discoursed and written upon what they are pleased to term the "finished work of Christ" or the "finished work of Calvary." Especially have the Plymouth Brethren emphasized this, and the phrase has become a pet one with them. They present the atonement as being objectively and subjectively finished at the same time, or rather that its subjective application in the first instance equals its objective completeness. And yet they are compelled to admit from experience and observation that atonement is not completed in us at its first application. What do they do to reconcile the inconsistency? They resort to this species of interpretation: The atonement, in its subjective application, is completed in us in the purpose and view of the mind of God. God makes our standing at the moment of our salvation in Christ as complete as it will ever be in the glorified state, and He refuses to view us in any other light but that of eternally saved beings glorified with Christ. What then? We are not glorified the moment we are saved. No, indeed. Our state of character is as imperfect before God as our standing is perfect in God's mind; according to the advocates of this theory. Perfection of standing in Christ is to them a most pleasing theme, while perfection of character in us is a most horrible doctrine. We are, according to this theory, as perfect angels in our standing before God, in Christ, and as imperfect as constant necessitated sinning can make us in character, upon earth. What is to be done? The Holy Spirit has come to bring our state up to our standing before God. This is the way they so teach. How the Spirit is to accomplish this is difficult to see, as we are constantly sinning before God and cannot keep from it. But we are to rest in the "finished work of Christ" imparted to us in the mind of God, and as we rest we are being perfected in state, corresponding, to our perfection in standing before God. This perfection of state is going on in us though we are constantly sinning against God. Sin cannot interfere, as it is put away in pardon, once for all, both past and future. Christ took all our sins, past and future, upon Himself and they are His, not ours, and we take His righteousness by faith, and God never sees our sins, but upon Christ, and He never sees us but as in the perfect righteousness of Christ, and hence sin has taken its eternal flight from the mind of God, and He can never see them again. They are Christ's sins, not ours, and as He put them all away, God sees no sin upon Him, and so they are gone eternally, even though we be sinning all the time. (this is clearly the use of projection as an ego defense mechanism)
We object to this-
(1) because there is no scripture that teaches perfection of standing, absolute, before God, and imperfection of state at the same time
(2) it does away with the necessity to prayer and faith, and all promises of reward for faithful service. All law is abolished, as they teach, and consequently, all duty is abrogated, all possibility of apostasy annihilated, and so we can go to sleep in carnal security, till death, and wake up in the bliss of glory eternal. This comes as near being a "damnable heresy" as anything we know."
What is the teaching of this theory as found among Pentecostal people? It is this: When we are saved the atonement is applied to us with a "finishing stroke," removing all sin of all kinds, so that we are sanctified wholly at the moment of pardon. We are of necessity completely cleansed from inbred sin at the moment of forgiveness and regeneration.
We object to this theory for the following reasons:
(1) it makes no distinction between the objective completeness of the atonement on the cross, and it's subjective completeness in the heart and life of believers, here and hereafter. That the atonement was objectively completed on the cross we gladly admit, and boldly teach.
Christ saith, "It is finished," and His word is true. God, the Father, accepted it as finished, and also all the host of Heaven. The Christian church has accepted, and taught it from Pentecost to the present without exception. But that the atonement is subjectively finished in us at its first application we stoutly deny. The Bible, which is the text book of the atonement, from Genesis to Revelation, does not so present the atonement as finished in us at the first application of its benefits. We have studied diligently the history of the Christian church, and also the history of its doctrines separately, from the days of Christ to the present, and we have never seen anything that even intimated that the atonement was subjectively finished in us upon the forgiveness of our sins. The finishing of the atonement subjectively in us has never been defined by any theological system in the Christian church for nineteen centuries except that which we have presented of Antinomianism and Plymouth Brethrenism. And they do not teach it so, absolutely.
(2) It is a limitation put upon the atonement. If the atonement is finished in the work of justification (for in that work we are sanctified, also, according to this theory) then there is no more to be done in, or for, us in its provisions, as they are granted or bestowed in this first and only work of grace. To say that it is finished in us in the removal of all sin is to affirm that all the provisions of the same are limited to the sin question and can go no further. If the complete removal of all sin of all kinds from the heart and life is the purpose of the atonement, and that when this is done all is done that was provided for, then there can be no further benefit bestowed upon us. If this is the finishing of atonement, it is finished. If it is finished, nothing more remains to be done; and if any more remains to be done, or given, then it is not finished. This means that when one work is done all is done. One application is the completeness of the whole.
The advocates of the "finished work" do not thus believe, for they teach that there are other experiences and blessings beyond justification. In this they are inconsistent and illogical.
The finished work of Christ is the removal of all sin from the heart, and a finished work is complete. When God finished the creative work it was complete, nothing more to be done. He rested at that juncture, and did not keep on creating. When Jesus said, "It is finished," the atonement was complete; he did not have to die any more. He gave himself "once for all" and there could be no repetition. Justification, according to this theory, necessarily embracing sanctification, both being one and the same thing without distinction in nature and time of reception, and this one work of grace being the "finished work of Christ," the whole atonement being applied in all its provisions, therefore, nothing more can be done. It is finished, and a finished work is a finished work; no more additions, or repetitions, the thing is impossible.
(3) We object to it because it places the greatest and most extensive work of God outside and beyond the atonement. We mention a few:
(a) The baptism of the Holy Ghost. This is promised in the Word, and we have always believed that it was provided in the atonement. We are mistaken, according to this theory, as the atonement is finished, and the whole of its provisions applied in justification. There is no relation between the Spirit and the blood, the one did not purchase the other. The ground of the Spirit's reception must be sought for elsewhere.
(b) The healing of the body. Isaiah 53 is the prophetic atonement chapter, and in it the healing of bodily diseases is explicitly stated as one of provisions of his sufferings and death. Matt. 8:17 plainly states that Christ "took our infirmities and bore our sicknesses" to fulfill this statement in Isaiah 53. And we have always thought since we accepted this truth of healing, that it was in the atonement, but in this we are in error, as the whole atonement is finished in the one work of grace removing all sin.
(4) The victory over the world and Satan is through the blood of Jesus, for "they overcame Him by the Blood of the Lamb, and the word of their testimony." The victory is through Christ, but not by virtue of His death. Victory has nothing do with the blood. We have always thought that Christ died to "deliver us out of this ungodly world," and have been simple enough to believe it, but in this we are wrong, as the atonement is entirely finished in the one work of grace, received in justification.
(5) We have been taught that through the precious blood we would enter through the gates into the City of Light; for it is said that the saints in glory give all the praise of their eternal salvation to the Lamb whose blood secured it for them. "These are they who have come up through great tribulation, and have washed their robes and made them white in the Blood of the Lamb. Therefore are they before the throne of God." It is rather disturbing to find in this we have been mistaken also, and we are at a loss to know just how to get to Heaven since the blood can not avail to help us, as its whole benefit is entirely and completely applied in saving us from all sin in the one work of grace.
Do not all these blessings come to us through the atonement of Christ? Yes, yes, shout all the advocates of the "finished work of Christ" in justification. Then we inquire, soberly, what do you mean by the "finished work of Christ?" You use it constantly to set forth justification as that which delivers from all sin. In that you say the work of Calvary is finished. If it is, then you should never preach another blessing or benefit beyond, because it is not in Christ, as nothing can come from or through Christ except His blood. If it is not so, then candidly, we say, be consistent, be honest, be sober, and quit using the phrase in relation to sin's destruction alone, as that is misleading, unscriptural and false.
In concluding this chapter we boldly assert that there can come no blessing, benefit, experience, or victory, in body, mind, or spirit, in time or eternity, except as it comes through the Blood of Jesus, and that alone. The blood purchased everything absolutely for us. The "finished work of Christ" subjectively does not end with this life." (end quote)
The doctrine of atonement/propitiation (prevalent among many mainstream groups in Christianity) is very controversial and questionable. There is a deception being propagated behind such doctrines to pervert God's grace into licentiousness. Please refer to my post "The deception behind the doctrine of atonement/propitiation."
Many Christians today are sociopaths. Satan has blinded them with sociopathic ideologies like Calvinism, which makes them think that God ignores and condones their evil behavior. They think they they live under the dispensation of grace and thus, they can freely sin without any consequences. They think they can abuse God and also their fellow human beings. I've learned that by knowing a person's view of salvation and sin, you can know if they'll make a good friend or moreover a spouse. Anyone who thinks they can abuse grace is the wrong person to befriend or be in a relationship with (they are sociopaths), as they will have the tendency to be abusive towards you, cheat on you, dump you, etc. Such people don't see anything wrong with themselves, and have a low rate of cure (changing themselves for the better). Thus, you'll be likely stuck with an abusive sociopath for the rest of your life while they destroy you and hurt you.
Calvinists and similar groups within Protestants project (an ego defense mechanism) their ongoing sinful behavior and the guilt of it onto Jesus Christ (this is done through their doctrines like imputed righteousness and penal substitutionary atonement). This is why they claim that all of their past, present and future sins are forgiven. By doing this, they suppress (another ego defense mechanism) the requirement for metanoia (change of heart/character) which the Bible clearly teaches. They just continue to sin without seeing the need to actually change. This in turn has created a sociopathic mentality in them (a dead conscience). They use circular reasoning (a sociopathic tactic) to justify their sinful behavior and the false doctrines they use for their defense. Projecting your ongoing evil behavior onto someone else will never help you to change. Instead, it creates sociopathic degenerates. Just look at the examples of Martin Luther (refer to "None dare call them sociopaths"), Martin Luther King, Jr. (refer to "Don't ever put your trust in humans"), George Sodini (refer to "As a Father"), the 400 pastors involved in the Ashley Madison website scandal (refer to "The carnal state of Christians/Apostasy"), and various "Christian" political leaders and pastors who are trying to redefine God's commandments given in the Bible (refer to "The destructive effects of sin excusing doctrines/ideologies"). They are only the tip of the iceberg. I've come across a Calvinist in recent times who had the audacity to question where sociopaths are mentioned in the Bible and what God's judgment is against them. It indicates that there are deluded "Christians" out there who think there isn't anything wrong with sociopathy. That's what is really scary. The Bible clearly describes sociopathy and condemns it (as well as narcissism) in passages like- 2 Timothy 3:1-9 and 1 Timothy 4:1-2. God's pending judgment against against such wicked people is clearly stated in so many passages. Couple of passages which come into my mind are- Matthew 13:36-43; Isaiah 13:11; Proverbs 11:21, etc. To list all of the verses in the Bible which deal with this is a difficult task. The following article cites verses which deals with the punishment of the wicked ("The Punishment of the Wicked"), however, I'm not sure if it's an exhaustive list.