In the gospel of John we find a prediction of Jesus that God the Father would send a Helper to be with the disciples of Jesus:

I (Jesus) will ask the Father, and He will give you (the disciples) another Helper, that He may be with you forever; that is the Spirit of truth … The Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all that I said to you. (John 14:16-17, 26)

When He, the Spirit of truth, comes, He will guide you into all the truth; for He will not speak on His own initiative, but whatever He hears, He will speak; and He will disclose to you what is to come. (John 16:13)

According to Jesus the Helper and the holy Spirit are one and the same. But Muslims say he is talking about Muhammad. Let’s see who is right. Jesus said to his disciples that this Helper ”may be with you forever”. But if he was referring to Muhammad, what kind of help would that have been for his disciples, considering that Muhammad came 600 years later? Therefore, Muhammad couldn’t have fulfilled this! Jesus also said that he would ”bring to your remembrance all that I said to you”. Did Muhammad do that? Did he teach his followers what Jesus had told about his death and resurrection?

From that time Jesus began to show His disciples that He must go to Jerusalem, and suffer many things from the elders and chief priests and scribes, and be killed, and be raised up on the third day. (Matthew 16:21)

Did Muhammad teach his followers that Jesus was put to death and raised up on the third day? No, he didn’t! Therefore, if Muhammad was this Helper Jesus predicted, then he definitely failed to ”bring to your remembrance all that I (Jesus) said to you”. Instead, Muhammad came with a totally different message. Instead of keeping the words of Jesus that ”love your enemies and pray for those who persecute you” (Matt 5:44), he decided to kill his enemies and rape their women. For me it’s obvious: Muhammad could impossibly be the Helper Jesus predicted. 

Just the fact that Jesus called the Helper ”the spirit of truth” gives us a clear indication that he did not spoke of a person but of a spirit. After his resurrection from the dead, he told his disciples that ”John baptized with water, but you will be baptized with the holy Spirit” (Acts 1:5). This happened on the day of Pentecost (Shavuot) just a few days later:

When the day of Pentecost had come, they were all together in one place. And suddenly there came from heaven a noise like a violent rushing wind, and it filled the whole house where they were sitting. And there appeared to them tongues as of fire distributing themselves, and they rested on each one of them. And they were all filled with the holy Spirit and began to speak with other tongues, as the Spirit was giving them utterance. (Acts 2:1-4)

What Jesus promised his disciples in John 14 had finally come true. The Father had given them ”another Helper, that he may be with you forever”. And this spirit would ”bring to your remembrance all that I said to you”. Finally, there is another interesting thing in the book of John, which most people seem to miss. In chapters 14 and 16 Jesus is talking about the Helper. And then, in the beginning of chapter 17, he says that

this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent (17:3).

Jesus reveals to his disciples how they can get eternal life, and that is through God the Father and Jesus himself. But if he had just talked about Muhammad as the Helper in chapters 14 and 16, why did he not mention this when he now reveals the way to eternal life? Why did he not say that the eternal life is through God the Father, Jesus and the Helper? Did he suddenly forget that he had just talked about Muhammad, or could it be, most probably, that he was not referring to him at all? For me, the answer is obvious. Jesus had no thought of Muhammad whatsoever when he spoke about this Helper, whom he called ”the spirit of truth”.