If you believe that kind and wise man, with a beard and long hair, our Lord and Savior, who was betrayed and killed, resurrected from the dead to our joy, raise and shout...

JON SNOW IS BACK, BITCHES!

But I’m calling it now: it will be revealed that wasn’t Melisandre’s magic what exactly brought Jon back... Jon warged into Ghost, voluntarily or not, when stabbed by the Alliser Thorne’s group, and either waited ‘til now to get back (by reasons to be revealed), or was pulled back as a side effect of Melisandre’s ritual.