"Jesus is Lord" as the Gospel

I recently had a discussion in which a person working with a basic law/gospel approach argued that affirming "Jesus is Lord" is not properly a receipt of the Gospel (and, hence, of justification), because Lordship is concerned only with authority and, hence, with law.

Aside from passages like Ro 10.9, which seem directly to contradict the claim, I think we should also resist the notion that Jesus' Lordship is "only" about obedience for at least two reasons.

First, if Jesus is Lord, then Satan isn't. "For [the Father] rescued us from the domain of darkness and transferred us to the kingdom of his beloved Son" (Col 1.13). Satan's dominion gives us death and condemnation; Jesus' Kingdom gives us forgiveness and life.

Secondly, in Jesus' kingdom, the one who rules is he who serves. "[T]he one who is the greatest among you must become like the youngest, and the leader like the servant. For who is greater, the one who reclines at the table or the one who serves? Is it not the one who reclines? But I am among you as the one who serves" (Lk 22.26-27). Matthew adds that "the Son of Man did not come to served, but to serve, and to give his life a ransom for many" (Mt 20.28).

Jesus is a peculiar Lord, at least by the world's standard. Submitting to his lordship means not that we work, but that we rest. "Take my yoke upon you and learn from me, for I am gentle and humble in heart, and you will find rest for your souls" (Mt 11.29).

So it seems to me that Jesus being our savior is inextricably tied up with Jesus being our Lord. Jesus establishing his lordship through the work of the cross is the Gospel. Receiving Jesus as Lord is receiving the forgiveness and salvation offered to us in the Gospel.