Scot McKnight has started a series on why he left Calvinism. It’s well worth the read.
From the post:
There are (so I think) two major weaknesses in Calvinism’s theology (and also a disorientation in its architecture): first, the emphasis of its architecture is not the emphasis of the Bible. Its focus on God’s Sovereignty, which very quickly becomes much less a doctrine of grace than a doctrine of control and theodicy etc, and its overemphasis on human depravity are not the emphases of the Bible. The overemphasis of these two in high Calvinism comes more from Augustine and later Calvinists than from the rhetoric of the biblical authors. I do not dispute the presence of these themes; I dispute their narratival centrality and they are where the gravity of emphasis is found in the Bible. Yes, we all have metanarratives that put things together, and Calvinism is one such metanarrative. It works for some; it simply didn’t work for me.
Second, the exegesis of Calvinism on crucial passages is sometimes dead wrong. I was once standing, years later when I was teaching at Trinity, outside my door talking with two professors about my view of Hebrews, when I simply asked one of them, “Who do you think best answers the Arminian interpretation of Hebrews?” [The warning passages] That professor said, “Philip Hughes.” I had just read Hughes and I thought it was weak. In fact, what I thought was this: “If that is the best, then there is no debate.” The other professor said, “I agree, Scot. Hughes doesn’t answer the questions.” Then he said, “I’m not sure any commentary really answers it well.” (Both of these professors were Calvinists, and still are, God bless ‘em.) What I’m saying is that the exegetical conclusions I was drawing (in all kinds of passages) were not answered adequately by the Calvinists I was reading. We all have to give them a fair shot. But at that time I had nothing to lose and it didn’t matter where I landed; I wanted to find out what the Bible said.