Personally I avoid the phrase "Believe in" I know what "Believe" means and I know what "In" is. The two words together do not make sense to me.
Having said that I am convinced that this body can be compared to clothes that we are wearing just for now. When it is appropriate we will discard this body and take on a new one. We are born, we die, we are born again.
Being convinced of something leaves me open to being unconvinced but this is where I stand at this time.