A.T. Robertson Commentary Luke 3:16

"John answered, saying unto them all, I indeed baptize you with water; but there cometh he that is mightier than I, the latchet of whose shoes I am not worthy to unloose: he shall baptize you in the Holy Spirit and [in] fire:" — Luke 3:16 (ASV)

He that is mightier than I (ο ισχυροτερος μου). Like Mr 1:7, "the one mightier than I." Ablative case (μου) of comparison. John would not turn aside for the flattery of the crowd. He was able to take his own measure in comparison with the Messiah and was loyal to him (see my John the Loyal). Compare Lu 3:16 with Mr 1:7f. and Mt 3:11f. for discussion of details. Luke has "fire" here after "baptize with the Holy Ghost" as Mt 3:11, which see. This bold Messianic picture in the Synoptic Gospels shows that John saw the Messiah's coming as a judgment upon the world like fire and the fan of the thrashing-floor, and with unquenchable fire for the chaff (Luke 3:17; Matthew 3:12). But he had the spiritual conception also, the baptism in the Holy Spirit which will characterize the Messiah's Mission and so will far transcend the water baptism which marked the ministry of John.