Do you think that Paul's claim that Jesus was "in the line of David" is legitimate? Why would Paul make such a claim? Why would someone think that a random homeless preacher from a poor family in Galilee was "in the line of David"? The claims that Paul makes about the nature of Jesus, when he does make them, are clearly being made on a scriptural basis. Jesus is "in the line of David" because the scriptures that revealed Jesus say so.