“If you want to save Christianity from atheism and Islam, [the] Trinity should be declared a heresy and false and [that] Jesus is Jewish [and] human prophet of God. If not atheism will take over Christianity and Islam will take over atheism.” - Syed Iftekharuddin
In other words, Christians must believe in the Islamic Jesus and reject the Trinity. That is, Christians must become Muslims. Why didn't Syed Iftekharudin just say that? Why his hidden dawah and taqiyya?
The Islamic Jesus shares nothing with the Christian Jesus save the name 'Jesus'. (Muslims even have a problem with that precise name, 'Jesus'.)
The Islamic Jesus:
i) Was simply "a prophet on the way to Muhammad".
ii) He was a Muslim. (Moses, in the Koran, apparently, wasn't a Jew either.)
iii) He did not die on the cross but "it was made to seem that way".
iv) He prophesied the coming of Muhammad.
v) He was married and had children.
vi) He was not the son of God.
vii) He went to Mecca.
viii) He does things in Islamic texts that no Christians texts acknowledge him doing (e.g., "preaching from the cradle").
The name and deeds of Jesus are just tools which Muslims use - "something we share" - at interfaith meetings (as well as elsewhere) in order to entice gullible Christians into Islam... it often works. In fact, it started with Muhammad himself who used both Jewish prophets and texts, as well as Jesus, as a neat and deceitful way to create a connection between his new invention, Islam, and those older faiths.
Muhammad knew he had to have a certain degree of shared ground in order to bring "unbelievers" or kuffar into his new religion. And that's exactly what Muslims are doing today in interfaith meetings, on the BBC, in Guardian articles, etc. You will find that once gullible Christians convert (or "revert") to Islam (simply because of the "shared Jesus"), Muslims will rarely talk about him. He will then become just another prophet who's only talked about on religious programmes on the BBC or at interfaith meetings. Muslims, amongst themselves, rarely talk about Jesus - if at all.
The problem with the Trinity that Muslims have is ridiculous. Although I don't fully understand the Trinity, the idea of one thing (of any kind) having three distinct aspects is not in the least bit self-contradictory. So why do Muslims often write, "1+1+1=1" in order to denigrate Christians? So much for interfaith!
Think of the British Government/state which is divided into three: executive, judiciary and legislature - "three in one".
Incidentally, there must be only between 200 and 500 words on Jesus in the entire Koran - and most of them are simple repetitions. There is no detail at all other than to say he was a prophet ("on the way to Muhammad") and other some minor details (e.g., "Jesus preached from the cradle").
The whole point of Jesus, in the Koran, is simply to place him in the prophetic line to Muhammad. Apart from serving that purpose, Jesus is not at all important in Islam. There are virtually no discussions, in the Koran, of what Jesus said and did. If his words and deeds do not serve Islam, they are ignored.
Jesus, again, is a tool of Islam. His memory and name are used by Muslims to further Islam and to persuade Christians to become Muslims. That is the purest form of dawah Muslims can indulge in. And bringing Christians "back to Islam" will helpt secure them a place in Islamic Paradise.