I've only been a Presbyterian for about seven years. So I know far less about John Calvin than I do about John Wesley, a founder of Methodism. Calvin, who founded a reformed movement that is represented in the United States by, among other denominations, the Presbyterian church, was born 500 years ago on July 10. One of the most difficult concepts for me is this:
John Calvin: On Double Predestination
In conformity, therefore, to the clear doctrine of the Scripture, we assert, that by an eternal and immutable counsel, God has once for all determined, both whom he would admit to salvation, and whom he would condemn to destruction. We affirm that this counsel, as far as concerns the elect, is founded on his gratuitous mercy, totally irrespective of human merit; but that to those whom he devotes to condemnation, the gate of life is closed by a just and irreprehensible, but incomprehensible, judgment. In the elect, we consider calling as an evidence of election, and justification as another token of its manifestation, till they arrive in glory, which constitutes its completion. As God seals his elect by vocation and justification, so by excluding the reprobate from the knowledge of his name and the sanctification of his Spirit, he affords an indication of the judgement that awaits them.
In other words, if I understand it correctly, some are born to be saints going to heaven, and others sinners going to hell. As one theologian friend of mine opined, "And you may THINK you have free will, but it was predestined that you think that."