Matthew 21:43- "Therefore I say to you, the kingdom of God will be taken away from you and given to a people, producing the fruit of it."
Jesus was not talking about Islam in that verse. Come to think of it, no where in the bible does in mention Islam. Do you know why? Because it is a false religion. Well, you know what they say: The truth hurts sometimes. Let me break down the verse so you can understand what it means.
The kingdom of God is the Church/Gospel. Jesus is saying the Church/Gospel will be taken away from the Jews and given to the Gentiles. God is taking the Church away from the Jewish nation and is giving it to another nation(Christians and all those, including Jews, who believe Christ died for them). As you see, this has been proven because now you see Churches everywhere and the Gospel is being spread everywhere. So it is producing fruit. If Jesus meant Islam, don't you think He would be saying that exact verse towards Christians? Jesus was specifically talking to the Jews. The kingdom of God was being taken from the Jewish nation, not Christians. If Jesus was talking to Christians, then your point would be valid, but He was talking to the Jewish nation who did not believe in Him.
Therefore, do not say Jesus "obviously" meant Islam. You would be spreading a false doctrine and will be making other people believe a lie. May the Lord bless you my friend.