Psalm 110 (KJV) is of interest to missionaries mainly because of two verses:
1: The LORD said unto my Lord, Sit thou at my right hand, until I make thine enemies thy footstool.
4: The LORD hath sworn, and will not repent, Thou art a priest for ever after the order of Melchizedek.

Critics claim this translation makes it seem as if the Lord is talking to my Lord—as if the same word, "Lord", is used twice. The argument asserts that the first LORD is the tetragrammaton (HaShem), while the second is adoni (master or lord with a small "l"), thereby supposedly removing any Christological reference.

However, this is exactly what we would expect under a functional subordination paradigm. Just as recognizing Christ's divinity does not negate His distinct role as the incarnate Son, saying "Jesus is Adoni" properly reflects the messianic function of Jesus, while His divine nature is established throughout the broader scriptural witness.

We also agree with the contention that this Psalm is referring to someone that is greater than David, which could refer to the Messiah. In Matthew 22:41-46, Jesus applies this Psalm to Himself.

The Christian understanding of verse 1, as per Acts 2:33-35, refers to Christ's ascension into heaven to sit at the right hand of the Father. Notice that verse 1 says that the second lord will sit at God's right hand until He subdues his enemies. Thus, there is no problem with the Christian interpretation that verse 1 occurred with Christ's ascension and that the other verses will be fulfilled in the future (or are in the process of being fulfilled now).