Bebaios (βεβαίως) is the adverb form of the adjective bebaios, meaning firmly, surely, or with certainty. It describes the manner of something being done or known with reliable certainty. While appearing rarely in the New Testament, its cognates (G949, G950) pervade the language of promise, covenant, and assurance.
Certainty is a gift of the covenant God. The Greek concept of bebaios — that which can be firmly relied upon — becomes in the New Testament a descriptor of God's faithfulness and of the believer's hope. Peter exhorts believers to make their "calling and election sure" (bebaian, 2 Peter 1:10). The author of Hebrews notes that "we have this hope as an anchor for the soul, firm (bebaian) and secure" (Hebrews 6:19). Faith is not wishful thinking; it rests on the firm character of the One who made the promises.