Dr. Jerry Walls gives a pretty good explanation of the heart of the differences between Calvinism and Arminianism. And I agree, it ultimately deals with the character of God. (Happy to see I'm not the only one who thinks this way!)
Which is why I have less problems (though I do have many problems) with the role of the pope or Mary in the Roman Catholic Church than with this issue. Watching both videos will take some time but I think he does a good job of explaining.
The first is introductionary, the second zooms in on the problem.
I have doubted if I could post this on NazNet. But NazNet, after all, is a Nazarene friendly site and its perfectly suitable for such a site to point out why in fact we are not Calvinists.