Mere denial of the divinity of ‘Eesa does not make Christians Muslims
4-12-2007 | IslamWeb
Question:
What is the destiny of Christians, in the time being, who believe that ‘Eesa (Jesus), may Allaah exalt his mention, is the Slave and Messenger of Allaah? Will they all enter Hell?
Answer:
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
If we assume that there are some Christians who believe that ‘Eesa 
is neither God nor the son of a God and that he is the Slave and Messenger of Allaah, then this mere acknowledgment will be of no benefit to them until they embrace Islam, adhere to its teachings and believe in our Prophet, sallallaahu ‘alayhi wa sallam. Allaah Says (what means): {And whoever desires other than Islam as religion –“never will it be accepted from him, and he, in the Hereafter, will be among the losers.} [Quran 3:85]
Moreover, in a Hadeeth on the authority of Abu Hurayrah 
the Prophet, sallallaahu ‘alayhi wa sallam, swore by Allaah that no Jew or Christian, who hears of him and dies insisting on disbelieving in him and in Islam, will be spared the torment of Hell. [Muslim]
indeed told his people to expect him. Allaah Says (what means): {and bringing good tidings of a messenger to come after me, whose name is Ahmad} [Quran 61:6] Allaah Knows best.