What exactly is the fundamental difference between Calvinism and Arminianism? Perhaps the conversation between Charles Simeon and John Wesley posted by Justin Taylor able to help us to understand:
[Simeon] Sir, I understand that you are called an Arminian; and I have been sometimes called a Calvinist; and therefore I suppose we are to draw daggers. But before I consent to begin the combat, with your permission I will ask you a few questions. Pray, Sir, do you feel yourself a depraved creature, so depraved that you would never have thought of turning to God, if God had not first put it into your heart?
[Wesley] Yes, I do indeed.
[Simeon] And do you utterly despair of recommending yourself to God by anything you can do; and look for salvation solely through the blood and righteousness of Christ?
[Wesley] Yes, solely through Christ.
[Simeon] But, Sir, supposing you were at first saved by Christ, are you not somehow or other to save yourself afterwards by your own works?
[Wesley] No, I must be saved by Christ from first to last.
[Simeon] Allowing, then, that you were first turned by the grace of God, are you not in some way or other to keep yourself by your own power?
[Wesley] No.
[Simeon] What then, are you to be upheld every hour and every moment by God, as much as an infant in its mother’s arms?
[Wesley] Yes, altogether.
[Simeon] And is all your hope in the grace and mercy of God to preserve you unto His heavenly kingdom?
[Wesley] Yes, I have no hope but in Him.
[Simeon] Then, Sir, with your leave I will put up my dagger again; for this is all my Calvinism; this is my election my justification by faith, my final perseverance: it is in substance all that I hold, and as I hold it; and therefore, if you please, instead of searching out terms and phrases to be a ground of contention between us, we will cordially unite in those things where in we agree.
(Cited in Handley Carr Glyn Moule’s 1892 biography, Charles Simeon, p. 79f.)