"Let anyone who is thirsty come to me and drink ..." (John 7:37-38)

"Let anyone who is thirsty come to me and drink. Whoever believes in me, as Scripture has said, rivers of living water will flow from within them." (John 7:37-38) 

What does 'whoever believes in me' mean?

Jesus says, "Whoever believes in me ..."

For centuries this statement has been interpreted as though Jesus is speaking about believing in him. Is this true? Within the context of the situation?

Since Jesus is right in front of the people he is speaking to, there is no question about them believing in Jesus’ existence. Rather the Greek word πιστεύω (pisteuō) being translated to “believes” means to trust - to "have confidence" and "to entrust."

Thus Jesus is speaking of their trusting in what Jesus is saying to them. Trusting in his teachings.

Why is trusting in Jesus' teachings so important to Jesus?
"My teaching is not my own. It comes from Him Who sent me. If anyone chooses to do God's will, he will find out whether my teaching comes from God or whether I speak on my own." (John 7:16-17)
Jesus is stating that his teachings are coming from the Supreme Being.

What is the 'thirst' Jesus is referring to?

Jesus is not speaking about literal thirst. He is not speaking of physical dehydration. Rather, this is a metaphor. An analogy.

The "thirst" that Jesus is describing in John 7:37 above is their thirst for happiness. Their thirst for fulfillment. This is provided by Jesus' teachings because his teachings are introducing them to the Supreme Being.

And those teachings will guide them back home to their relationship with God, which will quench their thirst for happiness. This is because loving and serving the Supreme Being brings us complete happiness.

What is 'living water'?

Jesus also states that if they trust in him and his teachings, then “living water will flow from within" them. What is this living water?

Again, this is a metaphor. "Living water" refers to a state of consciousness. It is a consciousness of loving the Supreme Being and loving others. Such a consciousness invigorates the soul. It is spiritual consciousness. Spiritual consciousness, according to Jesus, brings us life.

Such a consciousness defines the difference between someone who is alive spiritually versus someone who is dead spiritually. This same allegorical use of being alive or dead spiritually was also expressed when Jesus said:
"Follow me, and let the dead bury their own dead." (Matt. 8:22)
Thus, Jesus' use of "living" here is differentiated from anatomical life. Every physical body that is anatomically alive is maintained by a living spirit. The physical body is lifeless without the animation of the living spirit. Each of us is a living individual — spiritual in essence. Each spiritual individual originates from the Supreme Being.

This spiritual individual - each spirit-person - is not formless. Nor is God formless, as speculated by many. Each spiritual individual and the Supreme Being has form — spiritual form.

These spiritual forms are not visible by the physical eyes, however. This is because the Supreme Being designed the physical world in such a way that allows us not to see into the spiritual realm.

When the spiritual individual — who is driving the physical body and animating the body just as a car driver will start and drive a car around — decides to begin the journey home — back to their relationship with the Supreme Being — God will connect that person with His messenger, who will awaken the person to his true identity as the loving servant of God.

Jesus describes this awakening with the analogy of “living water will flow from within him.” That living water is love for God - which fueled Jesus' life and teachings.