In one reckoning, the second Sunday of Advent thinks about hope. Hebrews 11 might seem like a strange place to go for Advent. It is more usually associated with faith. But hope and faith are intricately connected in Hebrews 11.
Hebrews 11 does not give a definition of faith but multiple descriptions of faith. It's opening proverb is that faith is the stuff we have now of things we are hoping will come to pass. Faith is the proof we have now of things we do not yet see. In keeping with the overall meaning of Hebrews, Hebrews connects faith with continuing on in our journey through this world even though Christ has not yet returned. In this context, faith is about endurance. It is believing in the things for which we hope even though they have not yet materialized.
In the context of Hebrews, the invisible has to do with promises God has given us for the future. These are not promises not to suffer. Quite the contrary--Hebrews 11 is full of examples of people who did suffer on this earth, though they looked to a city and country that was yet to come. But we can of course expand the meaning to things we cannot see now too.
We can believe this year that God is in control, despite the fact that he allows a lot of things to happen we might want to change if we were God. We can believe that it is right to love our enemies and to live a selfless life, even though our human intuition tells us this is stupidity. And we can believe that one day, God will play out the final reset on evil that he started on the cross.