Jesus is prophesying of the giving of the Spirit, which is absolutely essential to the "circumcision of the heart," to "writing God's law on the heart," to enabling us to have a good relationship with God. Notice that He puts conditions on receiving the Spirit, which is a factor that did not appear much in the Old Covenant prophecies about it. But here the time to make the Spirit available is near, so God's Servant - Jesus Christ - tells us what the conditions are to be if we are going to agree to this Covenant.
He says that we have to believe, to come to Him. If we have been called, we have to respond. We have to thirst - to want it desperately - and on top of that, we have to drink. Remember the old cliché, "You can lead a horse to water, but you can't make him drink"? A lot of people are like that: They can be led to the truth, but to get them to take it in and make it a part of them is very difficult indeed.
In addition, the Spirit would not be given until Christ was glorified, that is, until after His death and His resurrection to spirit life.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part 12)
Christ spoke of the Holy Spirit during His proclamation on the Last Great Day. His words revealed that a day - the White Throne Judgment - would come when all humanity would have free access to the "living water" of God's Holy Spirit (John 4:13-14; Matthew 5:6; Revelation 22:17). Jesus is not only Judge of all, but also the One who dispenses the Holy Spirit to all of His disciples.
Martin G. Collins
Holy Days: Last Great Day
Giving meat in due season (II Timothy 4:2), Jesus preached about the meaning of the Last Great Day, and His subject was the Holy Spirit. Why? There is no doubt that some understood the meaning of the day because His audience had just witnessed the conclusion of a ceremony that involved water. God never commanded them to keep this ceremony, but nonetheless it contained a measure of true symbolism.
Each day during the Feast of Tabernacles, a priest drew an urn of water from the pool of Siloam and carried it through the Water Gate while the people recited Isaiah 12:3: "Therefore with joy you will draw water from the wells of salvation." Once inside the city, they paraded the urn of water to the altar accompanied by a choir singing Psalms 113—118. To conclude the ritual, the priest poured the water on the altar as an offering to God.
However, on the last day, the great day of the Feast, they marched seven times around the altar before pouring the water. What does pouring water upon an altar have to do with salvation? How many understood the symbolism that day when Jesus spoke concerning the Holy Spirit? Had the symbolism become obscured in people's minds by the passage of time? Jesus' comment should have revitalized their understanding of this wonderful truth.
Psalm 118:19-29 is a part of what the choir was singing as the procession approached and circled the altar. This psalm exalts the theme of the Last Great Day. It depicts the time when the whole world will go through the gates of righteousness, recognizing Christ as Savior, rejoicing in those God sends to teach them and praising God for His mercy in giving them salvation. Though not directly stated in these verses, the only reason mankind will respond like this is because God will pour out His Holy Spirit on all of humanity!
John W. Ritenbaugh
The Final Harvest
The Holy Spirit is the power of God—not a personage, entity, consciousness, or part of the Godhead or a trinity. The Bible speaks of the Spirit as the power or mind of God, the power of love and of a sound mind. It emanates from Him and thus can be said to be "poured out" (Titus 3:5-6), "breathed" (John 20:22), and used to "fill" (Acts 2:4) and "anoint" (Acts 10:38).
Martin G. Collins
The Holy Spirit
Other Forerunner Commentary entries containing John 7:38:
2 Timothy 1:7