For future reference these conversations should go something like this:

"Everything happens for a reason."

You mean god has a plan for everything?

"Yes, God is working his plan."

What about cancer?

"Well, we don't know what God's plan is."

Or you're wrong and god isn't working a plan. You could be wrong, right?

...at this point you'll either hear a smug and righteous "no", or the same smug attitude in some false humility "yes, it's possible I suppose, but..."

In either case it is your duty to laugh out loud, and I mean laugh man,and it shouldn't be fake because it is genuinely funny, and you should feel it when you laugh long and hard in their face.

They will feel insulted and rightly so, that's our intent, to insult harmful stupid when we encounter it.