God is real.. religion mostly is NOT.. even christian religion.. maybe even especially christian religion..
What would a real god have need of a religon, any religion.?.
No offense, but to ask this question you must be ignorant of the basics of Christian theology. Christianity exists not because God gets his jollies when we gather in a particular building to sing hymns. It exists because it is the vehicle to cure a great plague (sin) and the results for the patient, which is Hell.
One might as well ask why a doctor treats a patient who has Ebola. He gets nothing out of it except a chance to catch it and die horribly.