Here is a very good article that addresses common Protestant fallacy of irresistible grace, salvation by faith alone, and the related matters Assurance of Salvation?.
Wow, there is that Spirit of Love expressing itself again. And you want to lecture on this matter?
You must be a lawyer...
It may also be helpful to point out Augustine's writing on the matter of Predestination of the Saints
You'll find Augustine believed in irresistible grace. Perhaps he was the first Protestant, eh?