Elon Musk's religion or belief is still a mystery...
So far it has never been explained what religion he adheres to, but if we see from his love for his mother, then surely he is following his mother's belief or religion.
Being an atheist doesn't mean that their "RELIGION" is somehow secret. Their religion is right there, they don't believe in god or otherworldly existence, instead they believe in the practicality of everything, the proof of anything.
Also, atheist is not a description for somebody who don't have religion and in need to settle with one. Beliefs is not a embedded thought in a child planted by their parents, it is how one thinks and believes in something.
The trouble in the "proof religion" is, there isn't any proof that life could even exist... not in any way that we know of.
The only time somebody gets a glimpse of proof of his own life, is when he is in great joy or great pain. The rest of the time his religion is one of life without proof... one of all kinds of fictional imaginings.
If a person says there is no God, what he is actually doing is attempting to set himself up as god. How is he doing this? By thinking that he has enough mental muscle to logically get rid of the God idea in his life... especially since he knows that he doesn't know enough to actually KNOW that God doesn't exist.
