Excuse me for saying so, but isn't that kind of a dumb question? "We" can't "convince" Iran, currently in the iron grip of a bunch of theocratic lunatics, of anything, least of all anything to do with sharia law. "We" can only
- sanction Iran;
- invade it and throw out the nutbars in charge;
- do not invade, but do whatever we can to help Iranians throw out the nutbars.