This is a massive question! First, let me say Calvinism is a topic that will require many hours of study - if you really want to investigate it. Its been around for 500 years! So this blog post will only serve as a VERY brief introduction. Second, you have to know that Calvinism is very much alive . In fact, it was discussed in a recent TIME Magazine article that said it is one of the top 10 ideas changing the world right now. Calvinism is a very relevant and timely issue. Third, it is NOT a sin to believe in it. It is a belief system about God that has a great deal of biblical support and has endured the test of time.
That being said, what is it? Here is an introductory article from Challies.com. The author tells us...
"Calvinism is the theology that was a product of the Protestant Reformation and was largely defined by John Calvin (1509-1564). The doctrine emphasizes God’s omnipotence, man’s depravity and the salvation of God’s elect by grace alone."
"A Calvinist is someone who rejects the Arminian concept of free will, believing that the will of all humans is bound by their sinful nature and will remain bound until God performs His regenerative work. The two systems of theology diverge at the foundational issue of human depravity. Calvin says 'That man has the best knowledge of himself who most thoroughly knows his depravity.' Calvinism is founded on the belief that man is completely and utterly unable to make a choice to follow God because the will of the unsaved person is bound by his sinful nature."
Historically, the 5 main beliefs of Calvinism can be summarized using the acronym: TULIP
T Total depravity.
U Unconditional election
L Limited atonement
I Irresistible grace
P Perseverance of the saint
You can read a brief outline about TULIP in this article by Calvinist, Dr. John Piper. WARNING: It's long, but as I said before, Calvinism is a BIG topic.
On a side note, Calvin of the lovable duo, "Calvin and Hobbes" is named after John Calvin.
[Answered by Pastor HM]
