Probably God's greatest gift is his Son, Jesus Christ.
I'm currently watching The Nativity on BBC1. While it may be a bit twee, it's very biblical. Jesus' "father" was a humble carpenter. Mary was an ordinary young woman (the concept of "teenager" not quite existing back then). God chose them to provide the route where he could spread the Good News. He became a vulnerable baby, then a refugee. I wouldn't be surprised if he had problems making ends meet. He was viewed as mad by many and ultimately put to death for a non-existent crime by the Romans who were worried about his impact on their authority. I've mentioned a lot more about that last bit in my Holy Week series.
This is one of the best poems about it. Short, but worth reading.
Through all this, Jesus took the punishment for every sin that was ever committed or will be committed on himself. No need for animal sacrifices any more - we could now talk with God directly.
Jesus did not achieve a tremendous amount in his lifetime on Earth, but he set the stone rolling (literally on Easter Sunday). Three centuries later, even the Roman Empire, which had done so much to persecute Christians, became Christian. Even in our increasingly "Godless" society, people still have their children baptised and go for church weddings.
For all the problems that some in the Church has cause - Christianity has done a tremendous amount of good. From Jan Hus to William Booth to Mother Theresa, Jesus was God's ultimate present.