From peithō (to persuade, to trust). Confidence, trust, firm assurance. The settled conviction that comes from trusting in God's faithfulness rather than one's own abilities.
Paul speaks of having 'confidence through Christ before God' (2 Corinthians 3:4). This is not self-confidence but Christ-confidence — a boldness rooted in what Christ has done, not what we deserve. Such confidence allows believers to approach God's throne boldly (Hebrews 4:16), to face persecution without fear, and to persevere in ministry despite opposition.