The analogy of a play would help us properly dispose ourselves to the Simbang gabi masses leading to Christmas night.
In a play, after all the practices and all preparations, everything is ready for the event. The announcements are made and everyone is informed.
Three things make up a successful play: our presence, our participation, and our witnessing to the play. A play is a play when we are present and are properly disposed to attend it. Secondly, a play is a play when we participate; we are "in the play itself." Thirdly, we give witness to the play because of its profound effect in our lives.
The story of Christmas is the story of our salvation. It is God's story for us. But God said in the first reading that those who receive the gift are those who are properly disposed to receive it. Either we are absent from God or we are present.
Secondly, we participate by uniting ourselves in Christ who became one of us. We are affected fully by his words, actions, and being. We become like him. Finally, we give witness to Jesus by the conduct of our own lives. Jesus said, "My works testify that the Father has sent me." Only the conduct of our lives would give witness to Jesus if like him, we follow God's will.
Christmas may be the story of Jesus' birth. But it is the story of our rebirth as well. It is the story of our salvation in Christ Jesus our Lord.