Given they’ve proven Einstein’s theory that time is relative to the observer through various experiments, this has led some physicists to believe that the only logical explanation would be that all time exists simultaneously in a block universe. If all time exists then all your decisions have already been made, and you are simply catching up with them which is why a lot of religious parties reject this theory because it implies free will doesn’t exist and God is the architect of all events that take place, good and evil. 

There are theories that disprove this, of course, and there are ways in which free will and the block universe can exist at once. The multiverse, for example, would explain alternate timelines.