Justin Bieber: Shirtless And Ready To ... Get Baptized?

Justin Bieber looks like he's doing a plug for Calvin Klein or Jesus ... or both.

Biebs and his facial fuzz bolted from London -- after a wild weekend -- and touched down in South Beach to party at The Villa Casa Casuarina ... formerly Gianni Versace's mansion. Before Justin soaked up the rays and dipped in the pool, he also did lunch at Prime 112.