The following is an excerpt from The MacArthur New Testament Commentary on Luke 7.

Summoning two of his disciples, John sent them to the Lord, saying, “Are You the Expected One, or do we look for someone else?” (Luke 7:19)

Even the greatest man who ever lived up to his time (Matt. 11:11), John the Baptist, struggled with doubt. He had believed that Jesus was the Messiah. He had witnessed the testimony to His identity by the Father and the Spirit when he baptized Jesus. John had declared that Jesus was “the Lamb of God who takes away the sin of the world!” (John 1:29), and testified concerning His identity to the Jewish leaders (vv. 26-27). But despite his powerful witness to Jesus as the Messiah, doubts had arisen in John’s mind regarding His identity. This passage gives the reasons for John’s doubt, and Jesus’ response to that doubt.

First, John was experiencing a personal tragedy. His ministry had been the most significant of all the Old Testament prophets, since he was the forerunner and herald of the Messiah. John had faithfully, selflessly, and fearlessly carried out his prophetic duty. Yet despite that, he found himself locked in a prison cell. That seemed inconsistent both with his faithfulness, Messiah’s power, and God’s purpose. Surely the Messiah had the power to free him. And when Messiah came, bad things should have happened to evil people, not to His faithful forerunner.

A second cause of John’s doubt was popular influence. He was in part a victim of current misconceptions about the Messiah. Contemporary Judaism ignored the prophecies of the suffering (Ps. 22) and sin-bearing work (Isa. 53) of the Messiah, focusing instead on His coming to crush Israel’s enemies and establish His glorious kingdom. So deeply ingrained was the perception among the Jewish people that even after Jesus rose from the dead the apostles asked Him, “Lord, is it at this time You are restoring the kingdom to Israel?” (Acts 1:6).

Third, John’s doubt stemmed from incomplete revelation. Lack of information breeds doubt (cf. Matt. 22:29), and John was missing one crucial piece of information not clearly revealed in the Old Testament. It is true that the Old Testament implies two advents for Messiah, one as the suffering servant, and the other as the conquering king. But the Old Testament does not explicitly reveal the already 2,000-year gap between those two advents. During that time the Lord would turn from disobedient, rejecting Israel (Matt. 23:37-39) to the Gentiles and establish the church, which is made up of both Jews and Gentiles. Not until that period ends and all Israel is saved (Rom. 11:26) will Jesus return, establish His glorious kingdom, and fulfill all the promises of the Abrahamic and Davidic covenants.

The final and perhaps most significant reason for John’s doubt was his wrong expectation. John was a fiery preacher, warning of God’s impending judgment and calling for repentance (cf. Luke 3:3-17). His warning of judgment picked up where the Old Testament ended (Mal. 4:1), and John expected the Messiah to execute that judgment on the wicked when He arrived.