He came and He will return

From "The Evangelical's Guide to Advent":

.... So you grew up in a non-denominational, Charismatic, or Pentecostal church where the word Advent was never mentioned. Instead, Christmas was the celebration of Jesus Christ’s birthday expressed through jazzed up versions of Christmas hymns and the same two children’s Christmas plays on rotation every other year.

Now you’re older. Expanding your doctrinal understanding and searching for new faith traditions of your own. Like many young evangelicals, your curiosity has been piqued by liturgical traditions and their holy reverence foreign to your early church experiences. ....

Advent is the preparation for the commemoration of Jesus Christ’s birth and also a forward-looking celebration of His Second Coming. So Advent is not Christmas. ....

For our liturgical brothers and sisters, Advent marks the start of the Christian calendar year. For Western Christians, it begins after the Sunday closest to November 30 and extends until Christmas day. ....

...[D]on’t skip straight to the goodness of Christmas carols and nativity plays just yet. If you do, then you miss the biggest and best focal point that Advent has to offer—self-examination in preparation.

.... For Christians, the four weeks of Advent are a time for fasting and penitence in preparation for the feast celebrating the Christ’s birth. As my colleague Nathaniel Torrey explained, Advent is a time to humble ourselves in remembrance of “the profound humility of Christ as he became an infant to save us.”

.... Observing Jesus Christ’s birth is not complete without preparing, watching, and rejoicing over the coming of His return. .... (more)

The Evangelical's Guide to Advent