Jesus wants his apostles to stay and wait for the Holy Spirit who will empower them to go on a mission to help build his kingdom. The word kingdom was confusing to them and it can be confusing to us. We think of a kingdom, and we think of kings and queens, a physical territory,

potentially with walls and boundaries and stuff.  But that’s not what Jesus meant when he used the word “kingdom,” It is not a physical kingdom but a spiritual kingdom.