Why would Adonijah grab the altar? It wasn't just a decoration!
In ancient Israel, the altar wasn't merely a place for sacrifices. It also served as a sanctuary, a place of refuge. Anyone who fled to the altar was, in a sense, fleeing to God Himself for protection. Grabbing the horns of the altar was a desperate act, signifying he was putting his life in God's hands, trusting in divine protection even from a human king.
This shows us a powerful, albeit fear-driven, acknowledgment of God's ultimate authority and a plea for mercy in His presence. It's a recognition that even earthly powers are subject to a higher divine order.