Grace
If God gives someone the grace to be humbled and see the truth, and the doctrines are sweet to him, and they break his pride-because God chose him owing to nothing in him. He was awakened from the dead, like being found at the bottom of a lake and God, at the cost of his Son's life, brings him up from the bottom, does CPR, brings him miraculously back to life, and he stands on the beach thrilled with the grace of God-wouldn't he want to persuade people about this?
-from http://www.desiringgod.org/ResourceLibrary/AskPastorJohn/ByTopic/105/2765_Why_are_Calvinists_so_negative/
-from http://www.desiringgod.org/ResourceLibrary/AskPastorJohn/ByTopic/105/2765_Why_are_Calvinists_so_negative/