I find there is great confusion among people regarding the terms used on the NT and what exactly they refer to. I’m sure many others have given a nice, compact summary of these terms but this is the first one I’ve run across. It should serve as a handy guide in helping people understand what Paul is talking about when he uses one term as opposed to another. This is from Justification pages 104, 105

BOQ

First, as to terms.

1. Paul uses the word Jesus to refer to Jesus himself, Jesus of Nazareth, the human being who lived in the Middle East, announced God’s sovereign and saving rule, died on a cross, and rose again three days later.

2. When he uses the word Christ he denotes, of course, the same human being, but connotes the Jewish notion of “Messiah.”

3. When he uses the phrase Son ofGod, he means both that Jesus is the Messiah, the son of David whom God had promised would be his (God’s) own Son (2 Samuel 7:14 and elsewhere), and that the human being Jesus is to be identified as the one who was, all along, at one with “the Father,” and has now been sent from him (Romans 8:3; Galatians 4:4).

4. When he uses the word Lord, he means
a. that Jesus, precisely as the Messiah, is now exalted over all things;
b. that Jesus has attained the position of sovereignty over creation marked out for human beings from the beginning, as in Genesis 1 and Psalm 8;
c. that Jesus is therefore the reality of which all earthly emperors are mere parodies;
d. and, strikingly, that he is to be understood in the role regularly marked out, in the Greek Old Testament, as kyrios, which renders the reverent Hebrew adonai, which stands of course for YHWH (e.g., 1 Corinthians 8:6; Romans 10:13).

This complex but utterly coherent usage, in which Paul is completely consistent throughout his writings, forms the platform for what is to come.

Second, the meaning of Messiahship. Paul uses Christos, designating Jesus as the Messiah, in the conscious belief that the Messiah is the one in whom two things in particular happen.

1. “The Messiah” is the one who draws Israel’s long history to its appointed goal (Romans 9:5; 10:4). The single-plan-through-Israel-for-the-world was designed (so Paul believed, with many precedents in the Old Testament and second-temple Judaism) to culminate in the Messiah, who would fight the victorious battle against the ultimate enemy, build the new temple, and inaugurate a worldwide rule of justice, peace and prosperity. Paul, of course, saw all of these as being redefined, granted that the Messiah was Jesus (of all people!); but none of them is lost.

2. “The Messiah” is therefore the one—this is clearest in Paul, but there are significant antecedents—in ‘whom God’s people are summed up, so that what is true of him is true of them. To belong to the people over whom David, or David’s son, was ruling was spoken of in the Old Testament as being “in David” or “in the son of Jesse” (2 Samuel 20:1; 1 Kings 12:16). Paul can therefore speak of Christians as “entering into the Messiah” through baptism and faith, as being “in him” as a result. He is the “seed of Abraham,” not simply as a single person but because he “contains,” as the goal of God’s Israel-plan, the whole people of God in himself. The same point can be made by saying that Christians “belong to the Messiah”: “If you are Messiah’s, you are Abraham’s family, heirs according to promise” (Galatians 3:29). This is the key that unlocks some of the most apparently stubborn and tricky bits of Paul, not least in Galatians 2-4.

Third, the accomplishment of the Messiah. Going back to (1) in the previous paragraph, the task of the Messiah, bringing to its appointed goal the single-plan-through-Israel-for-the-world, was to offer to God the “obedience” which Israel should have offered but did not. It is striking that, in Romans 5:19, one of the most climactic ways in which Paul speaks of the accomplishment of Jesus the Messiah is in terms of his “obedience.” This is picked up, famously, in Philippians 2:8: he was “obedient to the point of death—even death on a cross.” But if Romans 5:19 thus looks back to the obedient death of Jesus, as Paul has referred to it in Romans 3:24-26, 4:25 and 5:6-11, he looks forward to exactly the same point with a closely correlated motif in Romans 3.

EOQ