Whose shoes I am not worthy to bear - The word translated here as “shoes” has a signification different from what it has in our language. At first, in order to keep the feet from the sharp stones or the burning sand, small pieces of wood were fastened to the soles of the feet, called “sandals.” Leather, or skins of beasts dressed, afterward were used. The foot was not covered at all, but the sandal, or piece of leather or wood, was bound by thongs. The people put off these when they enter a house, and put them on when they leave it. To unloose and bind on sandals, on such occasions, was formerly the business of the lowest servants. The expression in this place, therefore, denotes great humility, and John says that he was nor worthy to be the servant of him who should come after him.
Shall baptize you - Shall send upon you the Holy Spirit. The Spirit of God is frequently represented as being poured out upon his people, Proverbs 1:23; Isaiah 44:3; Joel 2:28-29; Acts 2:17-18. The baptism of the Holy Spirit is the same, therefore, as the sending of his influences to convert, purify, and guide the soul.
The Holy Ghost - The third person of the adorable Trinity, whose office it is to enlighten, renew, sanctify, and comfort the soul He was promised by the Saviour to convince of sin, John 16:8; to enlighten or teach the disciples, John 14:26; John 16:13; to comfort them in the absence of the Savior, John 14:18; John 16:7; to change the heart. Titus 3:5. To be baptized with the Holy Spirit means that the Messiah would send upon the world a far more powerful and mighty influence than had attended the preaching of John. Many more would be converted. A mighty change would take place. His ministry would not affect the external life only, but the heart. the motives, the soul; and would produce rapid and permanent changes in the lives of people. See Acts 2:17-18.
With fire - This expression has been variously understood. Some have supposed that John refers to the afflictions and persecutions with which men would be tried under the Gospel; others, that the word “fire” means judgment or wrath. According to this latter interpretation, the meaning is that he would baptize a portion of mankind - those who were willing to be his followers - with the Holy Spirit, but the rest of mankind - the wicked - with fire; that is, with judgment and wrath. Fire is a symbol of vengeance. See Isaiah 5:24; Isaiah 61:2; Isaiah 66:24. If this is the meaning, as seems to be probable, then John says that the ministry of the Messiah would be far more powerful than his was. It would be more searching and testing; and they who were not suited to abide the test would be cast into eternal fire. Others have supposed, however, that by fire, here, John intends to express the idea that the preaching of the Messiah would be refining, powerful, purifying, as fire is sometimes an emblem of purity, Malachi 3:2. It is difficult to ascertain the precise meaning further than that his ministry would be very trying, purifying, searching. Multitudes would be converted; and those who were not true penitents would not be able to abide the trial, and would be driven away.