The day is coming when the hold religion has over this world will break. The dark days ahead will do much to make people see that while religion can be good for community building, it brings disaster for the world at large. Of course, it's easy to blame religion for all of the world's ills, when in reality it has been greedy, hateful men using the cloak of religion to advance their nefarious agendas. Religion itself is like a gun. By itself, it poses no harm. But when wielded by psychopaths, it can be deadly.
After the World Revolution, many of the war's survivors will not only turn away from religion, they will actively seek its eradication. Whether justified or not, they will blame religion — at least in part — for the situation that led to the deaths of over half the world's population. Churches, synagogues, mosques, and temples will be torn down, tax exemptions will be revoked, the ruins of the Vatican (most likely destroyed during the war) will be cleared, and new laws will be enacted banning all public displays of religion. People will still be allowed to practice religion in their homes, they will simply be forced to keep it to themselves.
But religion will not go away. Nothing less than the extinction of humanity will eradicate religion completely. And while the followers of Faith will be forced to go underground, they will continue to pray. They will continue to worship. And as humanity branches into Offshoots and spreads throughout the galaxy, new pilgrims will depart Earth for greener worlds.
Far from the atheist and agnostic galactic powers, the religious will build new interstellar empires. Christians will create a Christ Divinity. Jewish people will build the Covenant of Stars. A new Star Caliphate will rise. The United Hindu Castes will exist peacefully in a quiet corner of the galaxy; the Wanderers of Buddha will travel the stars, seeking nirvana. Of course, even these empires will fracture and war against each other. The days will come when some ambitious tyrant seizes power, mobilizes his or her flock, and wage terrible wars of vengeance against the agnostic and atheist powers. In the end, though, as long as the Religious mind their own business and stay in their part of the galaxy, they will not be bothered.
The galaxy will be quite the crowded place. And I think it's time I described in detail the state of the galaxy at the time of Retrieval...