Where did Christianity originate?

Christianity originated in the city of Jerusalem in present-day Israel. The founder of Christianity, Jesus Christ, was born in the small town of Bethlehem, just a few miles southwest of Jerusalem. He was raised in the town of Nazareth in the region of Galilee, about one hundred miles north of Jerusalem. However, prophecy demanded that the Messiah come to Jerusalem, riding on a donkey, on a colt, the foal of a donkey" (Zechariah 9:9). The New Testament records Jesus riding into Jerusalem and only a few days later being crucified there. Two days later, on the third day, Jesus was raised from the dead. Jesus told his apostles to wait in Jerusalem for the sending of the Holy Spirit. Forty-nine days after his resurrection, on the Day of Pentecost, the Holy Spirit fell on the apostles as Peter preached the first public gospel sermon. All this is recorded in Acts chapter two. From its birth, with three thousand baptisms of the first day, the church rapidly grew in Jerusalem, later spreading to Judea, Samaria and Galilee in the following few years. Once the first non-Jews were baptized (Acts 10) the church rapidly spread outside what were traditionally Jewish lands into all the Roman Empire and beyond during the next three or four centuries.

A question arises, which is can we know from sources outside the New Testament whether the accounts in the New Testament are accurate history. This is a broad question, but the general consensus of historians is that the broad background of the history described above is accurate. Both the Jewish historian Josephus (late first century), as well as the avowed religious Jews who wrote the Talmud (second through fourth centuries) agreed that Jesus was a real person who did indeed die in Jerusalem. All the evidence we have points toward the fact that the earliest preaching of the gospel of Jesus Christ included the central teaching of his resurrection in Jerusalem. Therefore, it can be stated with confidence that the Church of Jesus Christ (Christianity) began in Jerusalem.
In the area now known as Israel/Palestine.