What does 1 Peter 3:7 mean?
In verses 1 through 6, Peter has given instructions to Christian wives about submitting to their own husbands and how to pursue true beauty. That teaching for wives follows naturally from commands to all believers: that we should submit freely to every human authority for the Lord's sake. But before moving on, Peter stops to briefly instruct husbands about how to live with their wives.The heart of the verse is that men should honor and respect their wives. Note, this would have been a radical idea in Peter's era. Particularly in comparison to modern society, women of this time period were oppressed, discounted, and often treated badly. Various versions of women submitting to their husbands would have been commonplace. Christianity's emphasis on "submission" to God ahead of the husband would have been unique by itself. However, the teaching that men should honor their wives, as equal, co-heirs of God's grace through faith in Christ, was revolutionary.
Driving the seriousness of this point home, Peter points to a consequence. Christian husbands who refuse to honor their wives will see their prayers hindered. Either God will not receive those prayers in full or the husband will find it difficult to pray. Any husband who is abusive, disrespectful, or otherwise belittling to his wife is defying the will of God—period. He must repent and change his behavior before that line of communication with God will be fully reopened.
Specifically, men are instructed to give honor to their wives "as the weaker vessel." Notice carefully that this does not say wives are actually weaker in any specific way. Rather, husbands must honor their wives "as" they would honor or care for something more fragile than themselves. The point is purely about how husbands are to treat their wives: as protectors.
Finally, husbands are commanded to live with their wives "with knowledge." This may mean with a growing understanding of who their wives are. Or, it may mean with the knowledge that God has given them a responsibility to give honor to their wives. In either case, the responsibility of the husband is very much the same.