At the beginning of Luke 7:31, TNIV and NIV2011 inserted some words which correspond to words that are only found in some inferior and late manuscripts that KJV appears to follow. The words are: “And the Lord said,”. These words are found in Stephanus’ Greek text, and also in the Geneva Bible, although not in Tyndale’s NT, since they are not in the Vulgate.
NIV probably did not follow Stephanus, but rather added the words based on the dubious interpretation that verses 29-30 is a comment by Luke rather than a portion of Jesus’ speech.
It is extremely unusual in Greek to start or continue a speech after an author comment without a speech introduction. The older NIV, following RSV, inserted an end of quote marker at 7:28, a parenthesis marker at the beginning of 29 and at the end of v. 30 and then a beginning quote mark at v. 30. The original Greek, of course, had no such markers, so this is an interpretation.
Although verses 29-30 do not occur in the parallel section of Matthew 11, that is not sufficient reason to assume that the words are a comment of Luke rather than the words of Jesus. Luke had other historical resources available to him than the book of Matthew. There are words of Jesus recorded in Matthew 21:31-32 that are similar in content to Luke 7:29-30, and there is no good reason to assume that these words in Luke were not part of the speech of Jesus.
Once the translators have decided that these words are from Luke, probably based on the KJV tradition, which is based on an inferior Greek text, then they add other words not in the text and mistranslate others. So, NIV says: “(All the people, even the tax collectors, when they heard Jesus’ words, acknowledged that God’s way was right, because they had been baptized by John. 30 But the Pharisees and the experts in the law rejected God’s purpose for themselves, because they had not been baptized by John.) 31 Jesus went on to say,…” The part with ”Jesus’ words” is not in the text, and what is implied from context is John and his message, not Jesus’ words. The translation of the aorist participle ”having been baptized” as a reason clause is dubious. The main verb is ”vindicate” and the two aorists indicate what went before the main verb. First they heard, then they were baptized (believing John is implied between these two events). The baptism was a means by which they indicated that they believed the message and that God was right in giving that message to John. Basically they are saying: ”You are right, God. We need to repent.” I don’t complain about NIV’s ”acknowledged that God’s way was right” although it is quite a lot of words to use to express ”justified God”. I do object to NET’s and CEB’s ”acknowledged God’s justice”.
In the preceding context Jesus has been commending John for the importance of his prophetic message of repentance (which people like the Pharisees rejected as the following text talks about). Verse 29-30 then says in a literal rendering from Greek: “And all the (common) people and the tax collectors having heard (him = John, or it = the message of John) and having been baptized with the baptism of John, vindicated God, but the Pharisees and the law-people not having been baptized by him, pushed aside God’s purpose/plan for them.” V. 31 then continues: “So (Greek: OUN), what shall I compare such people to…” referring to the Pharisees and law-people who refused to accept God’s plan and purpose for them.
In v. 29 we find the same word as in v. 35. “vindicated/justified”. In both contexts it refers to people who hear a message, believe it and act upon that belief. The common people and tax collectors who heard John’s message of repentance, accepted their need for repentance and were baptized. In so doing, they vindicated God and the message he had given his great prophet. The Pharisees and law-people had a different response. They did not believe that John was a true prophet, or at least they did not accept their need for repentance. Since they did not believe, they were not baptized by John and therefore put aside God’s good purpose and plan for them.
Unfortunately, this clear and simple message is clouded by so many English versions, including the newer ones like NIV2011, CEB and ESV. It doesn’t matter whether these versions belong to the literal or idiomatic camp, since they are all based on an interpretation and tradition that goes back to KJV or even further back. In this particular case the NIV2011 is more interpretative and misleading than the NLT.