Short answer
A great deal: belief in one Creator, in prophets such as Abraham, Moses and Jesus, in angels, scripture, prayer, charity and a Day of Judgement. The core differences are about God and Jesus. Islam teaches strict oneness with no Trinity, that Jesus is a prophet and not God or the son of God, and that Muhammad ﷺ is the final messenger.
A Muslim must believe in all of Allah's prophets, including Jesus, and in the original scriptures, including the Gospel. Believing in the Trinity, in the divinity of Jesus, or rejecting Muhammad ﷺ as a messenger is not compatible with Islam. The four schools and all Sunni scholars agree on this.
The four schools agree on this.
Explanation
Muslims and Christians share more than many people expect. Both believe that one God created the heavens and the earth and will judge every person. Both honour Abraham as a man of pure faith, Moses as the one who received the Torah, and Jesus as the Messiah born of the virgin Mary. Both believe in angels, including Gabriel, in heaven and hell, in prayer, fasting and charity, and in commands like honouring parents and not killing, stealing or committing adultery. See the Ten Commandments in Islam.
The differences are real and touch the heart of each faith:
- God: Islam teaches that Allah is one, with no partner, no son and no Trinity.
- Jesus: a great prophet and the Messiah, but a human servant of Allah, not God. Muslims believe he was not crucified but raised to Allah.
- Salvation: through faith in Allah and righteous deeds, with repentance made directly to Him, not through atonement on the cross.
- Scripture and prophethood: the Quran is the final revelation and Muhammad ﷺ the last messenger, sent to all people.
The Quran invites Christians to "a word that is equitable between us and you": to worship Allah alone. It tells Muslims to discuss with the People of the Book only in the best way, and says Christians are among the nearest in affection to the believers. Agreement on so much is a reason for kindness and honest conversation, not for blurring the differences. For a full comparison, read Islam and Christianity and can you be Christian and Muslim?
The evidence
Quran, Surah Aal-i-Imraan 3:64
قُلْ يَٰٓأَهْلَ ٱلْكِتَٰبِ تَعَالَوْا۟ إِلَىٰ كَلِمَةٍۢ سَوَآءٍۭ بَيْنَنَا وَبَيْنَكُمْ أَلَّا نَعْبُدَ إِلَّا ٱللَّهَ وَلَا نُشْرِكَ بِهِۦ شَيْـًۭٔا وَلَا يَتَّخِذَ بَعْضُنَا بَعْضًا أَرْبَابًۭا مِّن دُونِ ٱللَّهِ ۚ فَإِن تَوَلَّوْا۟ فَقُولُوا۟ ٱشْهَدُوا۟ بِأَنَّا مُسْلِمُونَ ﴿٦٤﴾
Say, "O People of the Scripture, come to a word that is equitable between us and you - that we will not worship except Allah and not associate anything with Him and not take one another as lords instead of Allah." But if they turn away, then say, "Bear witness that we are Muslims [submitting to Him]."
The Quran calls Christians and Jews to the shared ground of worshipping Allah alone.
Quran, Surah Al-Baqara 2:136
قُولُوٓا۟ ءَامَنَّا بِٱللَّهِ وَمَآ أُنزِلَ إِلَيْنَا وَمَآ أُنزِلَ إِلَىٰٓ إِبْرَٰهِۦمَ وَإِسْمَٰعِيلَ وَإِسْحَٰقَ وَيَعْقُوبَ وَٱلْأَسْبَاطِ وَمَآ أُوتِىَ مُوسَىٰ وَعِيسَىٰ وَمَآ أُوتِىَ ٱلنَّبِيُّونَ مِن رَّبِّهِمْ لَا نُفَرِّقُ بَيْنَ أَحَدٍۢ مِّنْهُمْ وَنَحْنُ لَهُۥ مُسْلِمُونَ ﴿١٣٦﴾
Say, [O believers], "We have believed in Allah and what has been revealed to us and what has been revealed to Abraham and Ishmael and Isaac and Jacob and the Descendants and what was given to Moses and Jesus and what was given to the prophets from their Lord. We make no distinction between any of them, and we are Muslims [in submission] to Him."
Muslims believe in all the prophets, including Moses and Jesus, without distinction.
Quran, Surah Al-Maaida 5:82
۞ لَتَجِدَنَّ أَشَدَّ ٱلنَّاسِ عَدَٰوَةًۭ لِّلَّذِينَ ءَامَنُوا۟ ٱلْيَهُودَ وَٱلَّذِينَ أَشْرَكُوا۟ ۖ وَلَتَجِدَنَّ أَقْرَبَهُم مَّوَدَّةًۭ لِّلَّذِينَ ءَامَنُوا۟ ٱلَّذِينَ قَالُوٓا۟ إِنَّا نَصَٰرَىٰ ۚ ذَٰلِكَ بِأَنَّ مِنْهُمْ قِسِّيسِينَ وَرُهْبَانًۭا وَأَنَّهُمْ لَا يَسْتَكْبِرُونَ ﴿٨٢﴾
You will surely find the most intense of the people in animosity toward the believers [to be] the Jews and those who associate others with Allah; and you will find the nearest of them in affection to the believers those who say, "We are Christians." That is because among them are priests and monks and because they are not arrogant.
The Quran speaks warmly of Christians as close in affection to Muslims.
Sahih al-Bukhari 3443
Sahih... والأنبياء إخوة لعلات أمهاتهم شتى ودينهم واحد ...
"The prophets are brothers from one father: their mothers are different, but their religion is one."
All the prophets, Jesus included, taught the same core faith.
Where the ruling is recorded
- al-Fiqh al-Akbar, the sections on belief in the prophets and the revealed books. States that belief in all the prophets and books is part of faith.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.