The general concept of these first three verses, teaches that in all cases, death frees a person from the claims of human law, and in our specific example, the death of a husband frees the wife from the claims of marital law. This release allows the woman to legally and legitimately marry again.
The example that Paul presents, is that of the wife with respect to her marriage to her husband. But this principle applies to both man and woman with respect to the marriage contract, in which case either is released from the marriage contract when their spouse passes away.
If a married person, regardless of whether they are the husband or the wife, has a living spouse, and they take up with another person, in the intimate sense, they are guilty of committing adultery. This principle should be well understood and common knowledge.
However, when the married persons spouse dies, then the marriage contract terminates, and the living spouse is free to remarry.
Everything in this world, and in this life, portrays a spiritual concept.
And in the case of marriage, this principle we are studying teaches the concept of being married to someone we did not choose and turned out to be a very bad marriage, versus being married to someone of our own choosing, which will turn out to be the very best of marriages.
In the example humanity assumes the role of the wife, and Jesus Christ assumes the role of the husband. Our relationship with Christ, is of course the best choice, however when we enter into this world we are married to the law through the sin nature, and therefore come under the law of that sin contract.
That original contract demands a payment of death, in order to get out of that contract.
Jesus Christ, paid our debt, and in so doing prepared the way for dissolving our first marriage.
When we believe in Christ, that symbolically identifies us with His death on the cross, and that death is the element that dissolves our original and unwanted marriage by means of the Mosaic law.
The Mosaic law gives us no way out of that first marriage. Just as symbolically, the wife is obligated, and responsible, and subordinate to her husband, then so too we, all of humanity, were originally obligated, and responsible, and subordinate to the law through sin.
Having been freed from that first obligation, and by our choice of Christ through faith, we are now bound to be obedient, and obligated, and responsible, and subordinate to Christ.
And of course our relationship with Christ, is developed and enhanced by means of our learning Bible doctrine. Bible doctrine in our soul, is in effect Christ in our soul, which is in effect the intimacy of the relationship that we have with God by means of doctrine.
Note too, that ignoring Bible doctrine, and living out of fellowship and apart from Christ, we are in effect committing an adulterous act with the former carnal life. Just wanted to make that clear.
Note too, that unbelievers, remain with their marriage with the Law through their refusal to believe in Christ and therefore are not adulterous, but are worse off because of their eternal condemnation marriage with sin, which is like keeping a functional marriage with a dead spouse, which sort of sounds disgusting, as it were.