Now faith is the assurance of things hoped for, the conviction of things not seen. Hebrews 11:1
Heb. 11:1 assurance. Greek hypostasis, also translated “confidence” (3:14). hoped for. On hope, see 3:6; 6:11, 18; 7:19; 10:23. conviction of things not seen. By defining faith (Gk. pistis) as “assurance” and “conviction,” the author indicates that biblical faith is not a vague hope grounded in imaginary, wishful thinking. Instead, faith is a settled confidence that something in the future—something that is not yet seen but has been promised by God—will actually come to pass because God will bring it about. Thus biblical faith is not blind trust in the face of contrary evidence, not an unknowable “leap in the dark”; rather, biblical faith is a confident trust in the eternal God who is all-powerful, infinitely wise, eternally trustworthy—the God who has revealed himself in his word and in the person of Jesus Christ, whose promises have proven true from generation to generation, and who will “never leave nor forsake” his own (13:5). Such faith in the unseen realities of God is emphasized throughout ch. 11 (e.g., 11:7, 8; cf. v. 3) and has provided confidence and assurance to all who receive Christ as their Lord and Savior.
– ESV Study Bible