The truth of Christianity simply hangs on two claims:
1) That Jesus was not only a first century Jew but also the Son of God who showed humankind how to have a relationship with God.
2) That this Jesus rose from the dead as witnessed and recorded by his first followers in the Bible.
Those who have decided to follow Jesus essentially believe the rational evidence of these two factors and have therefore committed their entire life to being with Jesus, becoming like Jesus and doing as Jesus did.