When people addressed Jesus as Lord, what did that mean?
My understanding is that it took some time before people recognized Jesus to be God in the flesh. There was a natural reticence due to their strict Jewish monotheism. I would say that none of the disciples recognized Jesus to be God in the flesh until after the resurrection, perhaps as many as 15-20 years afterward. I'm not sure that Mark even understood this by the time he wrote his gospel, though he was certainly approaching it. Still, they did indeed come to grips with it and in many and explosive ways. By the time Matthew wrote his gospel (about five years or so after Mark wrote his), it was beginning to be understood. By the time John wrote his (about four or five years after Matthew), there was a firm commitment to the belief in the deity of Christ.
One needs to carefully note the differences between what the disciples and others say about Jesus in the gospels, what Jesus claims for himself, and what the evangelist claims by way of later reflection. Three groups thus should be distinguished in terms of understanding and articulation: Jesus, those who knew him in the flesh, and later reflections by the evangelist.
Now, this presents some problems initially: How is it possible that the enemies of Jesus seemed to recognize his claim to deity while his disciples did not? For example, when Jesus forgives the sins of a paralytic, a Jewish leader says that he blasphemes because only God can forgive sins. Through the first half of Mark the disciples are seen wondering who Jesus is: they are loyal to him but are equally loyal to God. When he stills the storm they ask, "Who is this man who can still the storm?" It is a programmatic question that governs their thinking. At the turning point of the gospel (Mark 8:27-30), the disciples at least show that they have come to recognize that Jesus is the Messiah. But what does this imply? Militant conquest of Rome and establishment of God's kingdom on earth is foremost in their minds. But that the Messiah should die? Impossible! And when Jesus says that he will even rise from the dead (he mentions this three times in the second half of Mark), the disciples debated what this meant! Clearly, they don't have a category to put Jesus into.
Thus, when Jesus does the things that only God can do, when he says the things that only God (or a blasphemer!) can say, the disciples face a dilemma. They begin to realize that he is more than a mere man, but how much more? Is he a prophet, even the great prophet that they had been expecting? Yes, but is he more? The Messiah? Yes, but even more. What then? They dare not even think that he is claiming what they think he is claiming! To even utter this to one another would be blasphemous itself!
The wonder is not that the New Testament seems reticent to speak of Jesus as God, but that it even does so at all! That the later books (e.g., John, Titus, 2 Peter, Hebrews, Revelation) make very explicit
claims for Christ's deity shows that by this time the belief in his deity had become deeply entrenched in the early church. But keep in mind that almost until the destruction of Jerusalem in AD 66-70, many Christians (especially Jewish Christians) regarded themselves as Messianic Jewsthat is, they were still part of the Jewish community, but one that believed that the Messiah had come. Could this group of believers even entertain the notion that Jesus was more than Messiah, that he was indeed the theanthropic person? There was so much going against it that when the NT begins to make such hints by way of OT allusions, then implicit suggestions by calling him 'Lord' in a sense not used of others, then outright claims that Jesus was Savior (tantamount to claiming his divinity) and God, they had better be sure of what they were saying!
Your question, is one of Jesus' identity, rather than one of our recognition of his identity. Many evangelicals want to guard the deity of Christ so much that they refuse to look at things historically. By overshooting themselvesthat is, by seeing claims to his deity on the part of the disciples too earlythey end up short circuiting the argument, for they have a difficult time explaining how the earliest documents don't reflect such a high Christology. On the other hand, the very fact that all corners of the apostolic witness to Jesus reflect a progressive understanding of his true nature shows that their perception was rooted in the person of Christ.
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