This is a novel I read in 2015. It was an older book. The cover was black and hardcover. Don't remember any specific details. The book was in English. I believe it was from the 1980s or ‘90s.
It was set in the future where the world is united as one.
I'll try to outline all the major events that I remember, in as much detail as possible.
The story begins with a prologue of how a mutant gene called "The God Factor" was isolated and subsequently researched to reveal it gave humans reality-bending powers.
The first few test tube babies born with the gene were horribly deformed and could only lift light objects with their mind. However, with every subsequent generation they grew stronger until they could manipulate events on a universal scale. They were fitted with microchips which gave scientists complete control over them.
Using these people humanity became an interstellar civilization. Thoughts and ideas are no longer abstract as people with the God Factor can bring them into existence. The world government brings into existence "God", a manifestation of the collective faith of people, and places him in a zoo.
To mock death itself, the human race increases the biological lifespan of all humans by a trillion years, reasoning that, with unlimited resources and a universe too vast, they need as many people as possible. And that's where everything starts going wrong.
The protagonist is a scientist who works under the guidance of the scientist who was a part of the team that originally created the God Factor babies. He gets involved in a riot where 50 people immolate themselves, seemingly for no reason. Similar riots spread globally and on human colonized planets. The protagonist discovers that the reality benders have been siphoning energy from other universes to provide to their own and the continuous transfer of energy has caused the membrane separating different universes to weaken which causes severe suicidal tendencies in exposed people. Over 75% of the world population dies in a week as even the GF people are affected causing them to go supernova when dying.
The protagonist rushes to try and build a "reality anchor". It had a fancy name but I can't remember it for the life of me. As the world delves into anarchy, he used "God" to power it and restore the world's reality to it's original state. Then he discovers that he is in the lab which his mentor used to work in while they were working on isolating the God Factor gene. The book ends with him in a dilemma of whether to destroy the project once and for all or let it proceed and try to influence events in the future.
It's an amazing book and much deeper than I outlined here. It's very long and very thrilling.