I attended religious school all of grade school, never skipped my Catechist classes, and I didn't know what the Rapture was until reading the first book of the Left Behind series. It was a word and concept that I had never really considered.
"He ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead and his kingdom will have no end."
But that's what we are professing faith in at this part of the Creed. We are proclaiming that we believe that after Jesus rose from the dead, He returned to our Father in Heaven, and is now there, until the end of the ages. And when He returns, He will judge each of us. But the God's return isn't necessarily something we need to fear. Keep in mind that this is a moment to be excited for, this is when we will welcome our Lord in all of God's glory; it is a culmination of God's great and final plan for us.
It isn't a concept we often hear about in a regular Sunday Mass. It isn't something we seem to really think about. As Catholics, we're often more focused on the death-then-Heaven route. But we seem to forget there is also a point in time when time is actually going to stop. And you'll be out of time to run to Confession or receive the Anointing of the Sick. But we believe in this, just like we believe in the Trinity or Easter.
Whether we come face to face with God because God returns tomorrow or because we have died and returned to our true home, we believe in that second, better life. A life worth living well for now, because the life afterwards is simply put, so incredible.