The Greek Abraam (Ἀβραάμ) is the transliteration of the Hebrew Avraham (H85), originally Abram ("exalted father") and renamed by God to Abraham ("father of many nations" — Genesis 17:5). Abraham appears in the New Testament more than any other Old Testament figure — over 70 references. He is the central figure in the theological argument of Romans 4 and Galatians 3, and is listed first in the Matthean genealogy of Jesus (Matthew 1:1). He is the father of the faithful (Romans 4:11) — the paradigm of saving faith.
Abraham's theological significance in the New Testament cannot be overstated. Paul's entire argument in Romans 4 turns on the fact that Abraham was declared righteous before he was circumcised — demonstrating that justification has always been by faith, not works (Genesis 15:6 cited in Romans 4:3). Galatians 3 argues that all who believe are "children of Abraham" and heirs of the Abrahamic covenant — regardless of ethnicity. James 2:23 calls Abraham "friend of God" and shows that his faith was demonstrated by works (binding of Isaac). Hebrews 11:8–19 celebrates Abraham's faith as the gold standard of trusting God's promises when they seem impossible. Jesus's statement "Before Abraham was, I AM" (John 8:58) is a stunning claim to eternal preexistence that caused the Jews to pick up stones.