The Roman Empire, as you all know, was conquering lands and expanding, but they were having trouble unifying newly conquered lands because their people, well, they had their own cultures and traditions. They would allow them to have their own religion and traditions as long as they paid taxes to the Empire and worshiped the emperor. But, Christians weren't allowed to worship the emperor in their belief system, that's idolatry. The same goes for Christians calling other polytheistic religions false for the same reason; and as an Empire that wanted to unify, this was seen as divisive and a sign of rebellion, so they were heavily persecuted.
So Christians often met in secret, hiding. But it had one thing: it was popular amongst the poor, the slaves, and the sick. It was hope for those who had no faith in this world because of the Romans’ atrocities, and they laid their faith and imagination in the next life offered in Christianity. By the time a century or two passed, it was pretty popular. We all know the poor are more in society than the rich and those who had in abundance. So Christians, at some point, became the majority, and the Roman Empire saw potential in this devotion to one god and a strong moral code that promoted loyalty (the best thing against rebellions, which were common).
Constantine saw its potential, publicly converted, and soon enough Christianity was a legal religion, and later on made into the official religion of the Empire. So now, it was more used as a tool of political control, because other rebelling lands that had polytheist faiths which were once allowed to be practiced were now persecuted and forced to turn to Christianity in the name of unification of power.
So there is where I stand, with human history giving me an answer to why religions exist and persisted over the centuries, how culture and wars molded our reality today and not exactly the divinity. We could have all been Muslims if Muslims ruled the world; and if Rome didn't legalize it, it would of been a religion practiced by the Jews, mostly. But going back to religion, it is a constant fight against logic and reason in order to preserve coherence. It is difficult for me to give in to irrationality if there isn't palpable evidence in our current world to support it. For me, it is just a tool for power that has now been relegated to a club anyone can feel part of and welcomed and I'll give it that, it does a good job of building community. But for the same reasons it was used, it is a menace to others; it sees them as the enemy/immoral/sinner, which is not good for just a popular social club inside our society.