The Five Points of Calvinism (the “Doctrines of Grace”) as expressed in the Canons of Dort are not as precise to Calvinism itself as some would pretend them to be. They were precise externally in that they were a response to the Five Articles of Remonstrance (they highlighted the key disagreements that formed, what they deemed, a departure from Calvinism). But all through the history of Calvinism proper, men came to different conclusions within that system of belief. When James Arminius expressed concerns over predestination, his was not just one of two understandings. Calvinistic soteriology is not as univocal as some would make it out to be.
As I consider your experience here, I am struck that mine is very similar, only in the opposite direction. I have never attended a Calvinistic church, school, or seminary. I graduated, in fact, from a very non-Calvinistic seminary. II do not subscribe to a Confession. Yet following the “logical conclusion” of what would be considered “free-will” theology, I could not but come to the conclusion that God’s redemptive plan for all of creation rested in the hands of men. Still, that is not why I hold a Calvinistic soteriology. I chalked that up to “mystery”, and continued to argue against Calvinism for the same reason you oppose it now. I held, for that time, a view along the lines of Reformation Arminianism (God predestined all things – for example, God predestined the Fall in that he ordained, not that the Fall should occur but that in occurring it met his plan of redemption. God ordained, not decreed, such things).
But as you have taken to study, so did I. I found several intelligent and learned scholars (on both sides of the issue). Those who were Calvinists denied the conclusions attached to their belief. I looked at how God used Calvinistic preachers and missionaries. I quickly learned that the charge that the Calvinistic view of election leads to an anti-missionary stance was quickly disproven in real life. I came to realize that these Calvinists have worked out their faith, have worked out the consequences of the “points” to their “logical conclusions”, yet did not arrive where I thought they would have to end up. Out of the Calvinistic scholars, preachers, and teachers there existed none who taught that God was the cause of human sin.
I knew from philosophy that arguing “logical conclusion” was a meaningless fallacy. I knew treating my reasoning itself as superior was a baseless claim. So I simply set aside, the best I could, everything I read of Calvinism and all that I held about free-will, and studied my Bible. I came out holding a Calvinistic soteriology.
But, as I said, it is foolish to argue “logical conclusions”. I would never try to talk you, or anyone else, into holding my view if for you the only conclusion is God authors man’s sin. I would rather us fellowship in the truth of the gospel of Jesus Christ yet disagree than I would us be united in a soteriological view of how God accomplished salvation that left you believing God as the author of evil.