Who are they waiting on?
The follower's of Jesus are obeying his command to "wait" in Jerusalem for the Promise of The Father. This promise is none other than the 3rd person of The Trinity: The Holy Spirit.
The Holy Spirit is the one who was involved in creation as he hovered over the waters (Genesis 1:2). Early on The Spirit is seen present as early as the second verse of the first book of The Hebrew Scriptures. And The Spirit's participation is related to creation.
In the New Testament we read of similar activities in creating. Mary, the mother of Jesus, is told that the Holy Spirit will "come upon you and the power of the Most High will overshadow you; therefore the child to be born will be called holy, The Son of God (Luke 1:35). Jesus'' incarnation is the work of The Holy Spirit.
So, when Jesus declares that a religious leader that one cannot enter into the Kingdom of Heaven unless one is born of the Spirit (John 3:6)" he is declaring the creative work of The Spirit. Here we see the continuing work of creation of life as it relates to being "born again."
The Holy Spirit brings about new life in those who have faith in Jesus. Jesus makes this remarkable statement about The Spirit: "it is the Spirit who gives life (John 6:63)." This notion is supported by the Apostle Paul when he writes that the Holy Spirit regenerates and renews us (Titus 3:5).
So, these followers are waiting on the presence of the one who has been in the creation of life from the beginning of time. They have read the Hebrew Bible and heard Jesus' words about The Spirit and waiting to experience life like they have never known.
REFLECT: Are we trying to live the life of following Jesus in our own life or are we depending on The Spirit who creates and gives life?