What is "You gonna fly through the pearly gates with the biggest smile St. Peter ever seen." mean?

Question

A memorable quote on the beginning of the Pam Grier's 1973 action movie, Coffy. When the hospital nurse-turned-heroine who injects a second dope pusher with heroin in the bathroom who she got angry with him about her little sister, Lubelle who's involved with drugs as someone who's got her at it after Coffy shot the dope pusher in the brain with the shotgun in the living room said, "This is the end of your rotten life, you dope pusher!"

Answer 1

Coffy forces the pusher, at gunpoint, to take what is probably a lethal overdose of heroin, telling him, "Go on and take this shot!" The pusher replies, "I can't! That'll kill me!" Coffy says, "Maybe it will and maybe it won't, but if it do, you gonna fly through them pearly gates with the biggest f***ing smile St. Peter ever seen!" St. Peter, of course, is the keeper of the "Pearly Gates" of Heaven, and though the pusher may die from the overdose, he'll arrive at the gates with enough of the "happy drug" in him to make even a dead man smile. (Assuming he actually goes to Heaven; seems to me he'd be headed in the opposite direction.)