No, the God of Islam is not the same as the God of Christianity. In Christianity God is a Trinity, but in Islam God is not a Trinity. It is not possible to have God be a Trinity and also not a Trinity at the same time. Therefore, they cannot be the same.  Furthermore, because Islam denies the Trinity (that there is one God who is comprised of three distinct persons: Father, Son, and Holy Spirit), it means that in Islam, Jesus is not the incarnation of the second person of the Trinity.

• Quran, 5:73, “They do blaspheme who say: Allah is one of three in a Trinity: for there is no god except One Allah. If they desist not from their word (of blasphemy), verily a grievous penalty will befall the blasphemers among them.”
• Surah 4:171, “O People of the Book! Commit no excesses in your religion: Nor say of Allah aught but the truth. Christ Jesus the son of Mary was (no more than) a messenger of Allah, and His Word, which He bestowed on Mary, and a spirit proceeding from Him: so believe in Allah and His messengers. Say not “Trinity”: desist: it will be better for you: for Allah is one Allah: Glory be to Him: (far exalted is He) above having a son. To Him belong all things in the heavens and on earth. And enough is Allah as a Disposer of affairs.”

So it is clear that the Quran clearly denies one of the essential Christian doctrines about God’s nature being triune.  The God of Islam and the God of Christianity are not the same.

In Islam, Allah is a single person. Muslims consider their concept of God to be the proper one. They believe that Allah is all-powerful (Surah 6:61-62) and all-knowing (Surah 2:115; 10:61). They teach that he is the creator of all things (Surah 2:29; 3:191) and that he is the absolute judge of right and wrong.  In addition, the Quran says that Allah causes people to stray (Surah 2:26), does not love unbelievers (Surah 3:32) and that he is a deceiver (Surah 3:54).

Allah and Jesus

Also, in Islam Jesus is not God in flesh (Surah 4:172; 5:73; 9:30), where in Christianity he is (John 1:1, 14; Col. 2:9). In Christianity, Jesus was crucified, but in Islam, he was not (Surah 4:158). This is another irreconcilable difference between Islam and Christianity regarding God and who Christ is. In addition, Islam says that the Helper (paraclete in Greek) is Muhammed, where the Bible says that the Helper is the Holy Spirit (John 14:26). So, the God of Islam and the God of Christianity are not the same things.

However, we also need to point out a gross error on the part of Roman Catholicism regarding this issue. The Catechism of the Catholic Church says in paragraph 841, “The Church’s relationship with the Muslims. ‘The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind’s judge on the last day.'” The Roman Catholic church is wrong. Muslims and Christians do not worship the same God.