Religions are possessions of the Earth-based personality, and this attachment dissolves after the personality dies. Unfortunately, people forget the Truth and instead focus solely on the gift wrapping. People identify with their unique religious doctrines, their religion's shrines and rituals. In the process, people forget the Universal Truths that underlie all great religions. What is even worse is that people become competitive regarding their religious attachments.
People start to think that their religion is better than other spiritual systems.
When the animal instincts of survival and competition kick in, awful violence can ensue. Just reflect on the atrocities of the Christian Inquisitions and reflect on how the name of Jesus was used to justify acts of violence that he himself would have deplored. One can be a Jew in one lifetime and Islamic in the next. A person's religion is not part of the everlasting soul. Rather, religion is a garment that is cast off at the time of death.