We often think of “faith” as being a New Testament concept but it is spoken of numerous times in the Old Testament. Reading Hebrews 11 reveals that the ancients are said to have faith, being faithful, and having faithfulness.
Hebrews 11:1 defines faith “Now faith is the substance of things hoped for, the evidence of things not seen.” While the OT saints did not have the Spirit of God within, nor written Scripture as we do, they often had supernatural visitations via His voice, angels, or theophany or Christophany.
In Genesis 15:6 the Bible says that Abram “…believed in the Lord, and He accounted it to him for righteousness.” Abraham, Isaac, Jacob, and Joseph exercised faith in God and did great exploits- Hebrews 11:3-22 before the Mosaic law was given. Then we find that many others, living under the Mosaic law also did great exploits for God – Hebrews 11:23-40.
And we, who live under the New Covenant, are told in 2 Corinthians 5:7, “For we walk by faith, not by sight.” Galatians 3:11 says, “But that no one is justified by the law in the sight of God is evident, for the just shall live by faith.” Galatians 2:20 also says, “…the life that I now live in the flesh, I live by faith in the Son of God, who loved me and gave Himself for me.” And Hebrews 10:38 “Now the just shall live by faith, but if anyone draws back my soul has no pleasure in him.”
Faith in God is the God-given ability (Ephesians 2:8) to believe what He has said in His Word to the point that we can act on it, without any further external help. Although the Scripture does indicate the Spirit of God bears witness to us of the things promised in it (Romans 8:16-17).
The bottom line for New Covenant believers today is to believe what the Word of God says, obey it, and listen to the voice of His Spirit within, who always speaks and acts in line with the Word of God. And we will do these things because we believe, trust in, and know God that is and is a rewarder of those who seek Him (Hebrews 11:6).