"At that time Jesus came from Nazareth in Galilee and was baptized by John in the Jordan. Just as Jesus was coming up out of the water, he saw heaven being torn open and the Spirit descending on him like a dove. And a voice came from heaven: “You are my Son, whom I love; with you I am well pleased.” "

http://www.biblestudytools.com/mark/passage/?q=mark+1:9-11

...and...

https://www.google.com/search?q=jesus+helping+peter&tbm=isch...

...so maybe just water / splash resistance, and not a dive watch / water proof.

I hate to post a spoiler here, but near the end Jesus has something happen to his hand (or maybe it's his wrist) and there's a good chance he'd get blood on his Casio.

While he may well have had a Jesus number [1] Je >> 1, he would still be wet from e.g. splashing waves.

[1] The Jesus number is a dimensionless number in fluid mechanics; it is the inverse of the more commonly used Eötvös number, see https://en.wikipedia.org/wiki/Eötvös_number