Horatius Bonar emphasizes that true Christians are identifiable by specific marks that reflect their inner spiritual state. He asserts that a genuine believer will exhibit holiness, prayerfulness, zeal, consistency, humility, and self-jealousy, which are essential characteristics of a life transformed by faith. Bonar warns against the dangers of living in sin or worldliness, as these behaviors contradict the essence of being a Christian. He encourages believers to take their faith seriously, ensuring their lives reflect the light of Christ and the fruits of righteousness. Ultimately, Bonar calls for a life that visibly demonstrates one's identity as a child of God.

Theodore Epp emphasizes four essential marks of a Christian as outlined in Galatians. Firstly, a true Christian has Christ living within them, signifying a personal relationship with Him. Secondly, the presence of the Holy Spirit is crucial, as He transforms believers and shapes their character. Thirdly, Christians share in the experience of the cross, which is fundamental to overcoming personal struggles. Lastly, a Christian embodies a divine life that transcends mere external regulations, reflecting the transformative power of God.