Sound biblical doctrine is indispensable for living a faithful Christian life and fulfilling the church’s purpose—to glorify God, edify believers, and evangelize the lost. Paul’s letters consistently teach deep theology first, then show how it shapes daily conduct: love must abound in knowledge and discernment (Phil 1:9-10), believers must “walk worthy” of their calling (Eph 4:1), and walking in the Spirit is letting the Word of Christ dwell richly within (Gal 5:16; Col 3:16). Without diligent Scripture study, feelings and culture lead to sinful choices; but when truth fills the heart, the Holy Spirit guides every thought, word, and decision to magnify God.