How do we know the importance of preaching in Christianity?

The Bible highlights the essential role of preaching in the life of believers, as seen in 1 Corinthians 1:21, where it states that God chose the 'foolishness of preaching' to save those who believe. In the context of John 17, preaching serves as the precursor to prayer, underscoring that God's messages delivered through His appointed servants are powerful and transformative. Preaching allows the truth of the Gospel to be proclaimed, instructing and edifying the church while magnifying Christ. It is through preaching that God reaches the hearts of His people, calling them to repentance and faith.