Yes sir, the answer is straight forward. They do not need to become Muslims but they need to accept Jesus as the messiah, a great prophet and not a divine being or a divine son of God. If they do that the teachings of the Christ are almost the same like that of Islam. Though I am not an Imam but the verse in Quran "tell to the people of the book let us come to one word not to worship except God and not to take some of us (like Jesus) to worship instead of God.
Christians do not know how much this present anger to God. Muhammad (PBUH) used to tell Muslims not to praise him so they do not make him a God one day as Christians did with Christ. We commonly try to say about Muhammad "servant of God and his prophet". If Jesus is not a son of God biologically and not divine be assured he will be happy that you know his reality.
If Some Christians do feel animosity with Muslims or Islam that make them difficult to convert to Islam let it be. But your religion could be the truth if you to follow Christ as not divine. Give him all glory you like as a prophet not divine and you will be saved.
We are interested as Muslims to convey to you the truth. It is like you are spreading the good news of the gospel we will read the gospel as Muslims and we will carry the same good news of the return of the Jesus and the kingdom of God in earth.
