If there were a religion in this world aiming to defeat God as its goal, facing such a paradox that's like a cruel joke, I believe the vast majority would burst out laughing.
However, when it comes to human affairs, nothing is absolute, especially matters involving interests. No matter how they evolve and develop, there should be no surprise. Regicidal rebellion is one such matter, and so is deifying oneself after slaying a god.
Just like all organizations, the church at its inception was indeed devout and full of vitality. The clerics were sincere and simple, and it was common for them to immerse themselves among the common folk, sharing their joys and sorrows and assisting them. As time passed, the organization expanded, and bureaucracy and the idea of privilege gradually infiltrated and spread within the organization. The church had thus degenerated into a bloated organization only concerned with protecting its rights and seeking more power.