Here's the Apostles Creed - every major christain group adheres to this with only minor variations. It is a FUNDAMENTAL doctrine of Christainity:
1. I believe in God, the Father almighty, creator of heaven and earth.
2. I believe in Jesus Christ, his only Son, our Lord.
3. He was conceived by the power of the Holy Spirit and born of the Virgin Mary.
4. He suffered under Pontius Pilate, was crucified, died, and was buried.
5. He descended into hell. On the third day he rose again.
6. He ascended into heaven and is seated at the right hand of the Father.
7. He will come again to judge the living and the dead.
8. I believe in the Holy Spirit,
9. the holy catholic Church, the communion of saints,
10. the forgiveness of sins,
11. the resurrection of the body,
12. and the life everlasting.
NO OTHER religion believes this - therefore either Christianity must be false, or all others must be false.
Although Christianity originated as a Jewish sect, the two are widely contradictory, not least of which in the divinity of Christ - both can't be correct.
http://en.wikipedia.org/wiki/Christianity_and_Judaism
Islam has many concepts alien to other religions: eg martyrs are promised 72 houris - no other religion promises this - both can't be correct.
Etc etc etc - give it up.