Ascension Day marks the event in which Jesus went to the Mount of Olives with his disciples and ascended into heaven before their eyes (Acts 1:1-12). The Worship Sourcebook says, "Christ’s ascension means that in heaven there is one who, knowing first-hand the experience of suffering and temptation, prays for us and perfects our prayers. The ascension is a witness and guarantee of our own bodily resurrection, as well as an invitation for us to set our hearts and minds 'on things above, where Christ is seated at the right hand of God' (Col. 3:1-2) to rule over all things in heaven and throughout the universe (Eph. 1:10, 20-23)." 

As theologian NT Wright put it, “The point of the ascension is not that Jesus is going a long way away, but that he is being elevated to the true Lord of the world.” The ascension of Christ is the necessary prelude to Pentecost, “Ascension doesn’t mean absence, it means sovereignty, exercised through the Spirit.”