Why is that Jews and Christians do not believe in the Prophet Muhammad (pbuh)?

I haven't heard this one before, Masih. It would be helpful if you provided scriptural proof for your claim in the question. But I got the jist of your thought in 'Ephriam's' comment.

John 14:16 is not talking about Muhammed. I'm not sure where you would get that. Just a few verses later in John 14:26, John tells us that the "Helper" is the Holy Spirit (and Muhammed is not the Holy Spirit.

So your interpretation is impossible.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.