Lord is the title given Jesus in the second antiphon before Christmas. There are a number of times Jesus is called Lord in the Gospels and the New Testament. Some scholars would like to read this title as honorific, without reference to divinity, and at times the title is used this way. But there are a few particular moments worth consideration which suggest that Jesus is not simply a 'lord' in the accepted Mediterranean world in which the New Testament documents flourished.
First, the title is most unexpectedly introduced in Luke 5; here Peter calls Jesus 'Lord', after his experience of Jesus' teaching, then showing a wisdom considered divine. Such power, wisdom were usually associated with God; they not only suggest dominance over nature, but also a relationship with nature that is one of command-obedience. Jesus not only exhibits divine power, he also exhibits divine authority over the most diverse elements of human experience: nature, sin, death, demons, sickness. Peter did not know Jesus as Lord before his experience in Chapter 5. But that experience could only result, for Peter, in identifying Jesus as Lord.
A second moment is the end of Peter's Pentecost speech (Acts 2). Here, by virtue of Jesus' ascension, Peter sees Jesus as that Lord God invites to sit at His right hand. That seating is the culmination of the life that began in the womb of Mary. It is a life which, given its holiness, could only end, not in sacrifice, but in glory - the glory of the supreme judge of the world. It is not that Jesus did not exhibit Lordly powers on earth, but Peter indicates that Jesus reaches the fulness of Lordship upon his glorious heavenly throne.
Finally, the reluctance of Israel to pronounce the sacred four letters that we see forming the name of God, Yahweh, led to calling God Lord. Even though the title Lord appears in pagan literature of Jesus' time, one cannot assume that pagan culture as the definer of the word Lord when applied to him in the New Testament. The matrix of this definition is rooted in the Hebrew Bible; we cannot assume it is lost or changed because of a change in the culture in which the word was preached. Jesus is called Lord precisely against the known uniqueness of the title, that which belongs to Yahweh. The New Testament never offers a definitive answer to the question, 'how can a human being be divine?', but there is no doubt that it reflects a consistent effort to show the fundamental identity Father and Son enjoy: The Lord said to the Lord, as the Psalmist says.
It is this immensely powerful and authoritative person we celebrate as human at his conception and birth. May we enjoy his Lordship, so wise and powerful and holy - governed only by concern for our well-being.