God’s unconditional love does not imply that what we do doesn’t matter. Nor does believing that what we do matters imply that God’s love is conditional. The biblical truth is that God loves us unconditionally, and that is precisely why what we do matters.
Psalm 2 describes an idealized Israelite king as God’s Messiah. Jesus radically reinterpreted this idealization when he chose to exercise his Messianic authority through service, self-sacrifice, and trust in God. The Church, as co-heirs with Christ, now share in the Messianic privileges and responsibilities.
Commentaries are helpful, but the proper posture towards them, regardless of your knowledge of scholarship in the field, is one of resistance. By asking “How do we know that?”, you are positioning yourself to get the most out of your conversation with the Bible and out of the commentary.