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The Comforter = Holy Spirit.. Mohammed was never a "Spirit" he was a flesh and blood person whom people knew

A "Spirit" in the New Testament is a human Prophet. Therefore, Jesus had predicted the comming of a human Prophet (spirit) after him and not the Holy Spirit. Jesus would not have used the word "he" for the Holy Spirit. He would have used "it" instead in John 14:26 above. Read 1 John 4:1-3 below:

"Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world," (1 John 4:1-3)