My main beef against calvinism is the belief that God predestined certain people to be "elect"; in normal words, calvinists believe that God dictated who will be saved before that person was even born.
Now, that in itself is not so radical when you stop to consider how God sees time. But what is outragous is how calvinists believe that man has no free will in the matter.
I.e., man does not choose to follow God, God predestines man to follow God and be saved. So they believe that it's not: "Because you have faith in God and follow his ways, God will have mercy on you and save you." Instead, they believe it's: "Because God chose you, you will serve God and be saved."
You know Romans 9:15-18...
The calvinists suggest that this is the silver bullet proof that God predestines the elect. However, this is an incorrect interpretation. These verses are simply stating that nothing man can do by himself can get him into heaven. Man needs God's grace and mercy, which only God can grant. God grants mercy to those he grants mercy to, and we can presume from Jesus' teachings that God will grant mercy to those whose hearts are truly seeking God and who follow Jesus' path in heart, mind, and action.
If God has already elected those who are going to heaven, then why evangelize, seek to be saved, or even follow God's path?
Your traditional Calvinist would proclaim, "Because God told us so!" But if God has already elected those who will be going to heaven, no amount of influence from Christians will change who is elected or not. Evangelism may be the means of how God saves the elect, but our conscience decision to not evangelize will not affect the elect.
Yes, I believe God predestines many events. Many events throughout the Bible have been predestined. Jesus' birth was predestined. Jesus' death was predestined. Jesus' resurrection was predestined. Many things in our own lives could very well be predestined. But God certainly does not predestine people to go to heaven or go to hell. It is man's choice to either accept God's path or reject it.