The inner man is the spiritual and personal part of believers—their mind, heart, soul, and spirit—where God sees and works to transform them. Through regeneration and the ongoing work of the Holy Spirit, the inner being is renewed to grow in and reflect Christlikeness.
Scripture teaches that God reads hearts (1 Samuel 16:7; Psalm 44:21; Luke 16:15); He knows the inner self like no one else does—even more than us since we can deceive ourselves (Jeremiah 17:9-10). This spiritual and personal part of a person—mind, heart, soul, and spirit—is sometimes called the “inner man” or “inner being” (Ephesians 3:16). It is where God works to transform us (2 Corinthians 5:17). While outward actions are visible to others, God sees and evaluates the motives and attitudes of our inner person, holding us accountable to His standard of holiness for even our deepest and hidden selves. At salvation, believers are regenerated, receiving a new nature and the indwelling Holy Spirit (Titus 3:5-6).
But the new inner man battles against the old sinful nature (Galatians 5:16). Even so, the Holy Spirit, through the process of sanctification, progressively transforms our desires, will, and actions to reflect Christ (1 Corinthians 6:11; 2 Corinthians 3:18; Hebrews 2:11). The Holy Spirit shapes our inner self, and we cultivate that shaping through intimacy with God through prayer, Scripture, worship, and fellowship (Colossians 3:16; Acts 2:42; Hebrews 10:25). Over time, as we surrender and abide in Him, our inner man is renewed, producing love, joy, peace, and other fruit of holiness (John 15:4-5; Galatians 5:22-24). One day, our inner man will be fully conformed to the image of Jesus, enabling unhindered fellowship with God forever (1 John 3:2). Until then, we seek to abide in Him, allowing Him to transform us so we can grow and reflect Him to a world that desperately needs Him.
None of us is holy as God is holy (Romans 3:10-11). None of us have perfectly pure motives in our inner man to please God in all we think, feel, and do. Our hearts are sinful by nature and by practice. We need spiritual heart transplants. Thankfully, this is exactly what God does for His children (Ezekiel 11:19-20). The theological term for this spiritual heart transplant is regeneration. It is pictured also in Nicodemus' interaction with Jesus Christ. Jesus told Nicodemus that he must be “born again” (John 3:3). This assumes the spiritual deadness of humankind and the need for a new spiritual nature and heart (Ephesians 2:1-10). Men and women need nothing short of a spiritual birth (John 3:3), and this is what the Spirit of God provides through Jesus Christ (John 3:7-8).
Even with our rebirth in Christ, we still retain the sinful tendencies of our inner man. The actual process of transformation (referred to as "sanctification") is progressive.As we surrender and abide in God, we allow His Holy Spirit to transform us from the inside out so that our desires, will, heart, motives, and actions become conformed to His image.
We do this by cultivating an intimate relationship with God through prayer, reading God’s Word, and following His ways. We surrender and submit our thoughts, desires, and actions to Him. We prayerfully invite the Holy Spirit to renew our minds (Romans 12:2). Regular confession of sin and humbly relying on His grace keeps us dependent on Him rather than ourselves (1 John 1:9). Engaging in fellowship with other believers, worship, and service also shapes our inner man, providing accountability and opportunities to live out our faith practically. As we are transformed in our inner man, His life and love flow through us, producing fruit that reflects His holiness.