Is Islam the religion of God that accepts no other, what is the proof of that, and why have Christians not embraced Islam?

A Muslim is not permitted to doubt that Islam is the true religion, and that it is the religion of all prophets. Many verses have affirmed this, such as the Almighty’s saying: "And whoever seeks a religion other than Islam, it will never be accepted of him, and in the Hereafter he will be one of the losers," and "Indeed, the religion in the sight of Allah is Islam." As for some people not embracing Islam, this is because Allah guides whom He wills and leads astray whom He wills, according to His wisdom. He wrongs no one, but rather, people wrong themselves.