According to the context, the fire here is not the fire in Acts 2:3, which is related to the Holy Spirit, but is the same fire as in vv. 10, 12, the fire in the lake of fire (Rev. 20:15), where the unbelievers will suffer eternal perdition. John's word spoken here to the Pharisees and Sadducees means that if the Pharisees and Sadducees would genuinely repent and believe in the Lord, the Lord would baptize them in the Holy Spirit that they might have eternal life; otherwise, the Lord will baptize them in fire, putting them into the lake of fire for eternal punishment. John's baptism was only for repentance, to usher people to faith in the Lord. The Lord's baptism is either for eternal life in the Holy Spirit or for eternal perdition in fire. The Lord's baptism in the Holy Spirit initiated the kingdom of the heavens, bringing His believers into the kingdom of the heavens, whereas His baptism in fire will terminate the kingdom of the heavens, putting the unbelievers into the lake of fire. Hence, the Lord's baptism in the Holy Spirit, which is based on His redemption, is the beginning of the kingdom of the heavens, whereas His baptism in fire, which is based on His judgment, is the ending of that kingdom. Thus, in this verse there are three kinds of baptisms: the baptism in water, the baptism in the Spirit, and the baptism in fire. The baptism in water by John introduced people to the kingdom of the heavens. The baptism in the Spirit by the Lord Jesus commenced and established the kingdom of the heavens on the day of Pentecost and will carry it on to its consummation at the end of this age. The baptism in fire by the Lord according to the judgment at the great white throne (Rev. 20:11-15) will conclude the kingdom of the heavens.