In Buddhism, Islam, and Christianity there was a main event that is central to its respective religion. In Christianity, Jesus" death and resurrection is the central event. The call of Mohammed and the hegira are central to Islam while Buddha's enlightenment under the Bo tree is the main event in Buddhism. Each event is singular to its religion and attributes to its beliefs and teachings.
Christians believe that after the messiah, Jesus Christ, had spent about three years teaching the gospel, he was crucified for all of our sins. The Pharisee arrested him for heresy and whipped him and treated him very cruelly. Three days later he rose from the dead, proving he was and is the Son of God. To Christians, Jesus" death is very important. It shows how deep God loves us and how much He is willing to sacrifice for us. It is the epitome of Gods love for His people and also fulfills the scriptures. I think that the most important aspect though is Jesus opening the gates of heaven. It shows love as well, but it also demonstrates the measure of commitment that God/Jesus has with us.
In Buddhism, Buddha's enlightenment under the Bo tree is very important and central. What happened was that Siddhartha Guatauma sat under a Bo tree seeking enlightenment. As he sat there in deep meditation Mara, the evil one, tempted him. He surpassed these temptations and continued to meditate until he emerged the Enlightened One or the Buddha. This event is very important to the Buddhist religion. It is the moment when the Buddha started to teach. After sitting under the Bo tree in bliss for forty-nine days he emerged and was ready to share with the world what he knew. He was a great rationalist and a compassionate man, who taught what he believed, which in return started the religion of Buddhism. Mainly, Buddha's enlightenment was central to Buddhism because that is when the ideas from the Buddha were spread and thus started Buddhism.