Mark 1:8

“I baptised (drenched) you in water but he will baptise (drench) you in Holy Spirit.”

For this One Who is coming will be the means by which God will fulfil His promise of drenching men with the Holy Spirit (Isaiah 32:15; Isaiah 44:1). He will Himself be acting as the dispenser of the Holy Spirit, Who proceeds from the Father (John 15:26), a clear indication once it is thought through of His own deity.

This confirms that John's baptism in water was to be seen as a prophetic acting out of what was to happen, for the two are here spoken of in parallel. John could only symbolise the pouring out of the Spirit by a drenching in water, but the coming One would bring the reality by Himself sending, and drenching men and women in, the Holy Spirit (John 15:26). This demonstrates His true mightiness. He will bring to fruition the prophetic end of the age promises, the Messianic age, saturating God's people in Holy Spirit Who is at His disposal. The time of fulfilment is now at hand.