Yes, it is true that Deuteronomy 21:23 says “cursed is anyone who is hung on a tree/pole.” That is the whole point. When Jesus was hung on the cross, he received the curse of God that would otherwise have come on us. Paul makes this point in Galatians. He says in Galatians 3:13 that “Christ redeemed us from the curse of the law by becoming a curse for us, for it is written: “Cursed is everyone who is hung on a pole.” He redeemed us in order that the blessing given to Abraham might come to the Gentiles through Christ Jesus.” You see, that Muslims who make this charge simply do not understand the Christian message. The Christian message is that we were under a curse because of our sin, but Jesus paid the price for our sins so that we can be redeemed from the penalty for our sins. It was prophesied in Isaiah 53 that the Messiah would be “pierced for our transgressions” and “crushed for our iniquities.” (Isaiah 53:5). This prophecy was made several hundred years before Jesus came and more than a thousand years before the false prophet Muhammad incorrectly interpreted history. The fact is that Muslims deny that the crucifixion even happened, but history tells us something different. Muhammad denied the crucifixion, but history says it happened, and the New Testament tells us why it happened. So, the Muslim is using Deuteronomy 21:23 correctly, but applying it incorrectly to Jesus.