Because Jesus rose from the dead.
where did Christianity begin?
Yes you can say that as Christians follow his teachings .
It all began when god sent a message to David ( or somebody) that that God's son (Jesus) will be coming. That's when Christianity began (I think)
Christianity is said to have 'begun' at Pentecost, when the Holy Spirit descended to the apostles when they were in the upper room in Jerusalem. That would have been in ancient Israel.
30AD
Saint Paul
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Jesus Christ
Paul started Christianty
The Holy Bible.
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It was founded in Israel.