When Jesus Christ returns, yes everyone will believe, only because of the manner in which he returns. However, most will still try to pretend that it's not happening.
For those who believe that religion was an invention by man to gain control over an emerging society, they are simply foolish. In their worldview they would rather believe that the entire universe began when two items of nothing collided to create matter. It is extremely difficult for them to let go of their preoccupation that man and "nature" are in control, instead of a Supreme being (God).
To the man who says there were always particles of matter, I say who put them there.