Rather than hammering points home, often gentle persuasion can prevail, being logical and reasonable when laying out facts and truths.
Always, though, it is as you say, not by our power and might, but by HIS, through us!!
I have been known to hammer some points home.. 4 years ago when hitlery was running I cane this close to getting into a fight. Some hitlery supporter confronted me when I spoke ill of her heinous.. 30 minutes later, after the blood vessels went down in my neck he said he would vote for Lazio and for me if I ever ran.. Sometimes a person has to get louder than them to get their attention. You can't let them intimidate you. I tell everyone, don't ask my opinion if you don't want to hear the truth.