“You represent God as worse than the devil; more false, more cruel, more unjust. But you say you will prove it by scripture. Hold! What will you prove by Scripture? That God is worse than the devil? It cannot be. Whatever that Scripture proves, it never proved this; whatever its true meaning be. This cannot be its true meaning. Do you ask, “What is its true meaning then?” If I say, ” I know not,” you have gained nothing; for there are many scriptures the true sense whereof neither you nor I shall know till death is swallowed up in victory. But this I know, better it were to say it had no sense, than to say it had such a sense as this. It cannot mean, whatever it mean besides, that the God of truth is a liar. Let it mean what it will, it cannot mean that the Judge of all the world is unjust. No scripture can mean that God is not love, or that his mercy is not over all his works; that is, whatever it prove beside, no scripture can prove predestination.” — John Wesley
All Wesley does in this quotation is say that the Calvinist conception of God is worse than the devil, more false, more cruel, and more unjust. Taking that conclusion, he attempts to argue backwards by saying that, whatever evidence the Calvinist supplies, the conclusion will remain “that God is worse than the devil.”
As to his last statement, I will simply place Romans 8:28-30 and Ephesians 1:11, 12 for all to see:
“And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose. For those whom He foreknew, He also predestined to become conformed to the image of His Son, so that He would be the firstborn among many brethren; and these whom He predestined, He also called; and these whom He called, He also justified; and these whom He justified, He also glorified.”
“In Him also we have obtained an inheritance, having been predestined according to His purpose who works all things after the counsel of His will, to the end that we who were the first to hope in Christ would be to the praise of His glory.”