What is the difference between Islam and Christianity?

It depends on which part you compare, because the two faiths share a lot. Both believe in one Creator, prophets, angels, scripture, Judgment Day, heaven and hell, and both honor Jesus and Mary. The main differences are about who Jesus is, the Trinity, the crucifixion, original sin, and the role of Prophet Muhammad ﷺ.

What Islam and Christianity share

Many people are surprised by the common ground:

Belief in one God who created everything.
Abraham, Moses, David and Jesus as messengers of God.
Jesus' virgin birth, his miracles and his title "the Messiah."
Deep love for Mary. See What does the Quran say about Mary?
Prayer, fasting, charity, and a Day of Judgment.

Who Jesus is

This is the biggest difference. Most Christians believe Jesus is God the Son, the second person of the Trinity. Muslims believe he is one of the greatest prophets, but fully human and not divine. The Quran says:

إِنَّمَا ٱللَّهُ إِلَـٰهٌ وَٰحِدٌ ۖ سُبْحَـٰنَهُۥٓ أَن يَكُونَ لَهُۥ وَلَدٌ "Indeed, Allah is but one God. Exalted is He above having a son." Quran 4:171

Islam's core belief, tawhid, means God is absolutely One, with no partners or parts (Quran 112:1-4). See Do I have to believe Jesus isn't God to become Muslim?

The cross and salvation

Crucifixion: Christianity centers on Jesus dying on the cross and rising again. The Quran says he was not killed or crucified, but it was made to appear so, and God raised him up (Quran 4:157-158).
Original sin: many Christians believe humans inherit Adam's sin. Islam teaches Adam and Eve were forgiven (Quran 2:37), and "no bearer of burdens will bear the burden of another" (Quran 6:164). Every baby is born pure.
Salvation: in Christianity it usually comes through faith in Jesus' sacrifice. In Islam it comes through faith in God, sincere deeds and God's mercy, with direct repentance to Him, no intermediary needed.

Scripture and prophets

Christians follow the Bible (Old and New Testaments). Muslims believe in the original Torah and Gospel, but see the Quran as the final, preserved revelation. Muslims also believe Muhammad ﷺ is the last prophet, sent to all people, while Christianity doesn't accept him as a prophet. If you're coming from a Christian background, you can keep your Bible as a reference. See Can I keep my Bible after becoming Muslim?

Daily practice

Islam has a set daily rhythm: five prayers, fasting in Ramadan, zakat (yearly charity) and Hajj. Christian practice varies more between churches, with Sunday worship and sacraments such as baptism and communion. Islam also has detailed guidelines for food (halal) and dress.

Key points

Both faiths believe in one Creator, prophets and Judgment Day.
Muslims see Jesus as a prophet and Messiah, not God.
Islam rejects the Trinity, the crucifixion and original sin.
Muslims follow Muhammad ﷺ as the final prophet and the Quran as final scripture.

Tip: When talking with Christian family, start with Jesus and Mary. Sharing how much Muslims honor them often opens the door to calmer, kinder conversations about the differences.