Why is private prayer and the reading of Scripture so critical to building a relationship with God?

Sam Waldron explains in this video that private prayer and the reading of Scripture is incredibly important in the life of a Christian. If we are going to have a relationship with God, He is going to have to speak to us through His Word. We correspondingly speak to Him through prayer.

Without prayer and the faithful reading of Scripture, there cannot be a relationship with God. Every Christian ought to strive to have communion with God through prayer and reading His Word. But prayer and reading Scripture alone is not enough. There has to be a desire for God and a desire to hear from Him.

Ephesians 6:18 (NKJV) – “[P]raying always with all prayer and supplication in the Spirit, being watchful to this end with all perseverance and supplication for all the saints.”

I think I'm concerned about the individual godliness of Christians and their use, their careful use of the private means of grace. I believe that private prayer and the private reading of the Scripture are the very conduits of, well, eternal life. What I mean by that is that Jesus said in John 17, 3, this is eternal life that you might know God, the only true God and Jesus Christ whom He has sent. If we're going to have a relationship with God, He has to speak to us in His Word, and we have to speak to Him in prayer. Without those conduits, those tracts, there is no experiential relationship with God, and there is no eternal life.

So I believe every Christian does have communion with God in prayer and the Word, but I believe that prayer and the Word has to be much more than having devotions. There has to be life, there has to be an actual desire for God, desire to hear from God in our study of the Scriptures, and an actual speaking of the heart to God in our prayer.