15 And as the people were in expectation,  and all men mused in their hearts of John, whether he were the Christ, or not;
15 The people were waiting expectantly and were all wondering in their hearts if John might possibly be the Messiah.
15 As the people were in expectation, and all were questioning in their hearts concerning John, whether he might be the Christ,
15 The interest of the people by now was building. They were all beginning to wonder, "Could this John be the Messiah?"
15 Now as the people were in expectation, and all reasoned in their hearts about John, whether he was the Christ or not,
15 Everyone was expecting the Messiah to come soon, and they were eager to know whether John might be the Messiah.
Matthew Henry's Commentary on Luke 3:15
Commentary on Luke 3:15-20
(Read Luke 3:15-20)
John the Baptist disowned being himself the Christ, but confirmed the people in their expectations of the long-promised Messiah. He could only exhort them to repent, and assure them of forgiveness upon repentance; but he could not work repentance in them, nor confer remission on them. Thus highly does it become us to speak of Christ, and thus humbly of ourselves. John can do no more than baptize with water, in token that they ought to purify and cleanse themselves; but Christ can, and will baptize with the Holy Ghost; he can give the Spirit, to cleanse and purify the heart, not only as water washes off the dirt on the outside, but as fire clears out the dross that is within, and melts down the metal, that it may be cast into a new mould. John was an affectionate preacher; he was beseeching; he pressed things home upon his hearers. He was a practical preacher; quickening them to their duty, and directing them in it. He was a popular preacher; he addressed the people, according to their capacity. He was an evangelical preacher. In all his exhortations, he directed people to Christ. When we press duty upon people, we must direct them to Christ, both for righteousness and strength. He was a copious preacher; he shunned not to declare the whole counsel of God. But a full stop was put to John's preaching when he was in the midst of his usefulness. Herod being reproved by him for many evils, shut up John in prison. Those who injure the faithful servants of God, add still greater guilt to their other sins.