Ascension Day (celebrated today in the Western Church) is the day when Jesus’ return to heaven is commemorated. Luke 24:44-53
He left his disciples with the promise of the Holy Spirit to empower them to spread the Good News among all people. After he had gone, the disciples were promised that he would return. Acts1:7-11
God keeps his promises.
Ten days after Jesus ascended, the disciples received the Holy Spirit. (It was the Jewish festival of Pentecost.)
The Church celebrates Pentecost (or Whitsun) ten days after Ascension Day. Pentecost is also referred to as the Birthday of the Church.
We do not know when Jesus will return. 1 Thessalonians 4:13- 5:11
St Paul encountered Jesus on the road to Damascus. He was an unlikely convert. His story is told in the Acts of the Apostles, which was written by St Luke, who was an eye-witness to some of the stories he told. St Paul wrote letters to the Churches including two to the Church in Thessalonica.
May God himself, the God of peace, sanctify you through and through. May your whole spirit, soul and body be kept blameless at the coming of our Lord Jesus Christ.
1 Thessalonians 5:23 (NIV)