Whoever believes in me, as the Scripture has said, ‘Out of his heart will flow rivers of living water.’” (John 7:38 ESV) -Jesus Christ
What do you suppose flows out of the heart of a person who either does not believe in Jesus, or who believes in Jesus contrary to what the Scripture says?
“For no good tree bears bad fruit, nor again does a bad tree bear good fruit, for each tree is known by its own fruit. For figs are not gathered from thornbushes, nor are grapes picked from a bramble bush. The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks. (Luke 6:43–45 ESV)
If good is what flows out of the heart of the believer in Jesus, then evil is what flows out of the heart of the unbeliever. Which means that the river of water that flows out of this heart is not living, but dead; not refreshing, but contaminated.
When someone comes to your fountain to drink, are they contaminated or refreshed? The heart is the producing source of the water, and your mouth is the outlet. So again I ask, what flows out? Our text tells us that what flows out is directly connected to who we are believing in; either in Jesus (as the Scripture reveals him), not in Jesus, or in a mythical Jesus that has been made up.