Christianity is the only religion which believes that God became man. Some religions would even consider the idea of God's Incarnation blasphemous. Nonetheless, we Christians believe the Incarnation is the only hope for the world.
For example, the greatest religion next to Christianity is Judaism. Jesus chose to be a Jew. The Jewish religion realizes there is a very serious problem with the human race. We need a new heart (Ez 36:26). Judaism has recognized sacrifice as the best solution to humanity's problem. However, "it is impossible for the blood of bulls and goats to take sins away" (Heb 10:4). Thus, Judaism has no solution to the human predicament. It can only hope for the Messiah.
The Incarnation is the greatest event in the history of the human race. Thus, most of the world dates its years from the Incarnation. Catholics have traditionally prayed the "Angelus" at morning, noon, and evening to thank the Lord for the Incarnation. When we pray the rosary, we thank the Lord for His Incarnation as we meditate on the first joyful mystery and pray each of the fifty-three "Hail Marys" of the five-decade rosary. We are preoccupied with the Incarnation because it is our only hope.
We Christians should rejoice in the Incarnation always (see Phil 4:4). When anyone asks us the reason for this hope of ours, we must be ever ready to reply (1 Pt 3:15).