Sincere; Sincerity
What Does Biblical Sincerity Mean?
Biblical sincerity is far more than just being honest or earnest. It describes a fundamental quality of integrity that permeates one's entire being—thoughts, motives, and actions. The Hebrew word tamim (תָּמִים), often translated "sincere" or "uprightly," carries the sense of being complete, whole, or blameless (Joshua 24:14; Judges 9:16, 19). In the New Testament, several Greek words illuminate different facets of sincerity. Eilikrineia (εἰλικρίνεια) literally means "judged by sunlight"—something so pure it can be examined in full light without revealing hidden flaws (1 Corinthians 5:8; 2 Corinthians 1:12). Aphtharsia (ἀφθαρσία) means "incorruptibility" or freedom from decay (Ephesians 6:24; Titus 2:7). Adolos (ἄδολος) means "without guile" or "unadulterated" (1 Peter 2:2). Together, these terms paint a picture of transparent integrity before God.
Sincerity in the Old Testament Narrative
In the Old Testament, sincerity is primarily about wholehearted devotion to Yahweh. Joshua's famous challenge, "Choose for yourselves this day whom you will serve... But as for me and my household, we will serve the Lord," is immediately followed by the exhortation to "serve him with all faithfulness" or sincerity (Joshua 24:14-15). This sincerity involves putting away foreign gods and committing fully to the covenant. The concept appears in wisdom literature as well, where the "blameless" or "upright" person (from tamim) walks in integrity (Proverbs 10:9; 11:20). Sincerity is not about sinless perfection but about a consistent, undivided heart orientation toward God.
Sincerity in the New Testament Community
The New Testament emphasizes sincerity as essential for authentic Christian life and community. Paul repeatedly highlights it as a hallmark of his ministry and a requirement for believers. He states that his conduct in the world has been "with holiness and sincerity that are from God" (2 Corinthians 1:12). He contrasts sincere and insincere motives in preaching Christ (Philippians 1:15-17). For the Christian community, sincerity is critical: believers are to celebrate the festival (a metaphor for the Christian life) "with the unleavened bread of sincerity and truth," having cleansed out the "old yeast" of malice and wickedness (1 Corinthians 5:8). Peter encourages new believers to crave pure spiritual milk "like newborn babies" so they may grow up in salvation (1 Peter 2:2), with some translations emphasizing the "sincere" or "guileless" quality of this nourishment.
The Challenge and Expression of Sincere Faith
Biblical sincerity is tested in motives, speech, and love. Paul warns against those who preach Christ from selfish ambition rather than from pure (hagnos) motives (Philippians 1:17). He instructs Timothy to be an example in speech, conduct, and "in sincerity" (Titus 2:7). Perhaps most powerfully, Paul concludes his letter to the Ephesians with a blessing for all "who love our Lord Jesus Christ with an undying love" or "in sincerity" (Ephesians 6:24). This suggests that the ultimate expression of Christian sincerity is a love for Christ that is incorruptible (aphtharsia)—not subject to fading, hypocrisy, or ulterior motives. It is a love that endures and remains pure.
Cultivating a Sincere Heart
How does one develop this biblical sincerity? Scripture suggests it begins with God's work of grace and requires ongoing human response. The psalmist prays, "Create in me a pure heart, O God" (Psalm 51:10). This purity of heart is the foundation of sincerity. Believers are then called to actively pursue integrity, examining their motives (2 Corinthians 13:5) and living transparently before God and others. It involves rejecting hypocrisy—the disconnect between outward appearance and inward reality that Jesus condemned in the religious leaders of his day (Matthew 23:27-28). The community of faith serves as a context where sincerity is both nurtured and protected through accountability, truthful speech (Ephesians 4:25), and mutual love "without hypocrisy" (Romans 12:9).
Biblical Context
The concept appears across both Testaments, though the vocabulary differs. In the Old Testament, the key term tamim appears in historical narratives (Joshua, Judges) and wisdom literature (Proverbs). It describes the wholehearted, undivided devotion required by the covenant. In the New Testament, a cluster of Greek terms (eilikrineia, aphtharsia, adolos, hagnos) appears primarily in the epistles of Paul (1 & 2 Corinthians, Philippians, Ephesians, Titus), Peter (1 Peter), and once in the Gospels (implied in Jesus' condemnation of hypocrisy). It functions as a crucial ethical standard for Christian character, ministry motivation, and community life within the early church.
Theological Significance
Sincerity matters because it reflects the nature of God and the integrity of the gospel. God is truth without falsehood (Numbers 23:19; Titus 1:2), and his people are called to reflect his character. Sincerity is essential for true worship—God desires truth in the inner being (Psalm 51:6). It protects the gospel message from being discredited by hypocritical messengers (2 Corinthians 4:2). Furthermore, sincerity is evidence of genuine salvation and the Holy Spirit's work, producing fruit that includes faithfulness and goodness (Galatians 5:22). It is not a means to earn salvation but a necessary outworking of a heart transformed by grace.
Historical Background
The Greek cultural milieu prized certain virtues related to sincerity. Philosophical schools like the Stoics and Cynics valued authenticity (autarkeia) and living in accordance with nature/truth. The Greek term eilikrineia was used in legal and commercial contexts to describe something unalloyed or genuine. In the Jewish context, the Old Testament concept of tamim (whole, complete) was closely tied to covenant faithfulness and ritual purity requirements. The biblical authors, particularly Paul, appropriated and infused these existing terms with distinctively Christian meaning, grounding sincerity not in philosophical ideals but in the character of God and the transformative power of the gospel. The early church's emphasis on sincerity also served as an apologetic, distinguishing Christian ethics from the hypocrisy sometimes observed in pagan religious practices and even within certain Jewish sects (like the Pharisees as portrayed in the NT).