John 3:16 - "For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life."
Now I interpret this verse to mean that individuals have the choice to believe or disbelieve, as they see fit. Not everyone does. Some Christians argue that God causes believers to believe, and prevents disbelievers from believing. Phrased another way, John 3:16 is about faith (at least, in the context of this discussion), and faith, as a gift from God, is dispensed to whom He will, and not to others. As neither you nor I can compel God to dispense the gift of faith or any other gift, John 3:16 means God will only save those He has chosen to guide, while causing others to stray.
Note, the preceding is not my interpretation. I believe strongly in free will, and I believe that we choose to believe, to act on that belief, to follow God or to remain in sin. I'm just pointing out that not all Christians agree on that point.
Rom. 9:15-16 - "For he saith to Moses, I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion. So then it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy."
Again, I do not interpret this passage as suggesting that we have no freedom of choice, that God picks the recipients of his mercy and no individual will or desire has anything to do with it. I just point out these verses because some Christians read them as meaning, more or less, that God guides whom He wants to guide, and leaves in sin whom He wants to leave in sin.
Rom. 9:21 - "Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour?"
So then he who denies freewill argues that God makes the sinner a sinner, and makes the penitent main of faith the penitent man of faith, and that we cannot resist the power of God.
What do you think?