How do we know Abraham was a believer?

Abraham’s belief is confirmed in Hebrews 11:8-10, where it states that by faith, Abraham obeyed God's call and looked forward to a heavenly city. This faith is central to his righteousness, as Paul writes that Abraham believed God and it was credited to him as righteousness (Romans 4:3). More than mere belief, Abraham's life exhibited trust and obedience to God's promises, which is the hallmark of a true believer. His faith was not only a personal belief but also an enduring covenant with God that has implications for all who believe.