Today is Christmas, the day of Christ's birth. Now, we don't know if today was really the day he was born, but that's not really the point. The point is, God, the Holy God in heaven, became man, became a tiny baby humble enough to be born in a STABLE.
And why? What did it do to serve Him? NOTHING! Coming to earth and being born in Bethlehem was of absolute no use to Him! Then why did he do it? Why did the Lord and Creator of the Universe decide to clothe Himself in human flesh and be born as a baby?
He was born to die.
Now, every baby who gets born will die at some time or another (or at least most will), but Jesus' whole purpose in being born as a tiny baby in Bethlehem was to die! And why did He come to die? It wasn't for Him - He would have much preferred not dying, indeed, in the Garden of Gethsemane He prayed that the cup be taken from him - no, he came to die for us. He, the Creator of the Universe, Lord of all Creation, came to earth, was born as a tiny baby, so He could grow up and die so He could take our place, so he could take our sins and wash us white as snow.
People like to keep Jesus in that manger. If He stays in the Manger, they don't have to worry about Him being the almighty God who has the power to judge them forever. Indeed, His Justice REQUIRES Him to punish those who do not accept the world. They argue that if he's a loving God, he wouldn't send any to Hell. Yes, he is a loving God, but he's also Just, and a Just God cannot allow sin into heaven.
He sent Jesus to be born in that stable so He could die on that cross because he is a Loving God. By having Jesus die in our place, his Justice was satisfied, and his Love allowed us a way to get to Heaven.
But people don't want to accept this. Why? Why would they turn down an offer like this - Jesus, the Son of God dying in there place so they can get to Heaven? Because they don't want him to follow his rules. If they admit that Jesus is Just, then there are Rules, rules like no lying and stealing, no coveting, no messing around outside of marriage. Even though their lives would truly be so much better if they followed these rules, they don't want to follow them.
Yes, Jesus was born in Bethlehem and laid in a Manger - but he didn't stay there. Indeed, if he had only come to stay in that manger, he would never have come at all.