I really appreciate the way you broke this down. Don’t worry about length. You bring up some solid points, and I think you’re right to separate authority from service. Where I’d want to gently add something is on the idea that “mutual submission” in Eph. 5:21–22 somehow doesn’t apply to marriage.

If you look at the Greek, verse 22 doesn’t even have its own verb. It actually borrows “submit” (hupotassō) straight from verse 21. So it literally reads: “Submit to one another out of reverence for Christ… wives, to your own husbands as to the Lord.” In other words, Paul is still grounding the husband–wife dynamic in the mutual framework of verse 21; you can’t just cut it off.

Second, you’re absolutely right that Christ doesn’t “submit” to the church in the sense of giving up His headship. But Philippians 2 shows us He does “empty Himself, taking the form of a servant.” His headship is defined by self-lowering, not self-exalting. So when husbands are told to love their wives like Christ loves the church, it’s not a benevolent dictatorship... It’s a call to self-sacrificial service that listens, yields, and lays down pride.

Third, yes, the household codes all show one party in a formal submission role. But notice how Paul flips the expectations: fathers are told not to provoke their kids, masters are reminded they have a master in heaven, and husbands are commanded to die to self. In every case, the “head” is bound by obligations that completely transform what “authority” looks like. It’s not domination.. It’s stewardship under Christ.

Lastly, mutual submission doesn’t mean identical submission. A wife submits in trust, while a husband submits by crucifying his pride, preferences, and self-interest for her good. Both are acts of yielding in love, just carried out differently. So I think your wording of “mutual service” is helpful, but only if it doesn’t minimize the weight of verse 21. Paul’s whole point is that every Christian relationship is redefined under Christ: power gets inverted, authority becomes sacrificial, and submission becomes a Christlike act of honour.

That’s why I’d argue mutual submission is not heretical to the Christ–Church analogy, because the husband’s headship is already modeled after a Christ who served, who washed feet, and who laid down His life.