He first (αυτος πρωτος). Note πρωτος (nominative), not πρωτον, as in John 20:4; John 20:8. God loved us before we loved him (John 3:16). Our love is in response to his love for us. Αγαπωμεν is indicative (we love), not subjunctive (let us love) of the same form. There is no object expressed here.