The Greek form Achaz is the transliteration of the Hebrew Achaz (H271), meaning "he has grasped" or "he has held." It appears once in the New Testament (Matthew 1:9) in the genealogy of Jesus Christ. Ahaz was one of the most wicked kings of Judah, who burned his son as an offering, worshiped idols, and even closed the temple doors — yet he appears in the messianic lineage as a reminder of grace.
Ahaz is best known historically for the famous encounter with the prophet Isaiah (Isaiah 7:10–17), where God offered him a sign and Ahaz refused — cloaking faithlessness in false piety: "I will not test the Lord." God gave the sign anyway: "A virgin will conceive and give birth to a son, and will call him Immanuel" (Isaiah 7:14). The wicked king who refused to trust became the unwitting recipient of the greatest promise in Scripture. Matthew's inclusion of Ahaz in Jesus' genealogy declares that grace flows through unlikely vessels, and no one is beyond God's redemptive purposes.