I've come across Calvinists who have ridiculed man's free will and even related it to idolatry- in their twisted logic they think that man takes credit for their salvation if free will is true. What does the Bible have to say about free will?
Calvinists believe in unconditional election. They believe that God unconditionally predestined them to become saved (i.e. their free will wasn't involved in their salvation). They paint God out to be a sociopath who unconditionally chose them to receive eternal life and rejected everyone else to suffer eternal damnation. They believe God overlooks/ignores their ongoing evil behavior while not giving the same special treatment to everyone else (this is promoted through their doctrines like imputed righteousness, penal substitutionary atonement, and limited atonement). Calvinists and similar groups within Protestants further 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.