I think the truth lies somewhere in the middle between the Calvinists and the Arminianists (sp?) They both got part of it right, then went too far. Arminians discount man's depravity and God's grace, and Calvinists discount man's responsibility. Or something like that; maybe I'm not drawing the line quite right either (been a few years since I researched it) 
ETA: The truth has to accommodate the "whosoever" in John 3:16 and the "elect" and "predestined" in several of Paul's letters.
Sure. Also has to account the God's idea of justice in Ezekiel 18. Or the idea in 2 Peter 2 that one can be saved, but then also lose that state of grace again. Or again in 2 Peter 3 that God desires
all to be saved.
When simpler and numerous explanations lead in a different direction than the more complicated and rarer explanations, I suggest its reasonable to start from the simple and try to understand the complex from that. In other words, if the conclusion from the complex contradicts the simpler explanations, then the interpretation of the complex is where we are wrong, not the interpretation of the simple.
But backing up from that, I think it interesting that when confronted with Gnosticism and similar philosophical issues, the apostles and prophets did not argue these things from a philosophical or theological stand. But rather, they focused on the simpler facts that ought not to be denied. In John's case of confronting Gnostics, he explained exactly what love of God looks like (its obeying) and that Jesus came in the flesh, despite the conclusions that the Gnostic might have come to. But he never really confronts the core assumptions and speculations of the Gnostics, only the erroneous conclusions.
In Peter and Paul's case of confronting the Jewish/Christian hybrids, they explained it is OK to be circumcised, just don't require that of others. And gentile Christians should avoid doing things that stir up strife.
Which reminds me of the instruction to Timothy, to avoid arguing about myths, genealogies. And to not permit teaching of strange doctrines [I think the implication is public teaching, but not sure on that]. These things focus on speculations rather than the things we know we ought to do (in the context, "love from a pure heart and a good conscience and a sincere faith"). Paul goes back to saying, keep the instruction focused on the real things people need to avoid, lawlessness, profane, murderers, immoral, homosexual, kidnappers, liars, perjurers, and whatever else is against sound doctrine (1 Tim 1). These things (righteousness behavior) is the doctrine of God, not high ideas of philosophy.
The way these various speculations and ideas are treated, it seems that the apostles are willing to allow people to search out these things as much as they want, as long as they aren't creating division and arguments over it. AND as long as they aren't inventing ways to do what is plainly wrong (denying Jesus, denying baptism, accepting divorce and remarriage, lust, hatred, greed, etc).
So circling back to what Calvin and Luther and Zwingli and Popes and Arminians have taught, I don't really care what they speculated, as long as they do not contradict the things which is clearly commanded.
