Reading other people's mail can be fun, although usually in a perverse way. Information and comments addressed to someone else seem to provide insight into that other person's life and character. Having this insight, do we not then also have power over this other person? Do we not enter into the very essence of who they are, do we not begin to have some influence over what they will be and do?
Probably not. And so we deceive ourselves, first of all, and may try to play the actual reality game blindfolded. That is not known to be a best strategy for playing our own game well.
But if there is any amount of truth behind this illusion of magical power, that would be no argument for reading other people's mail. Reading other people's mail for the purpose of shaping their lives is an attempt to play the actual reality game for someone else. Who am I to play the game in someone else's place? The goal for me should be to make my own play in the game.
In the Bible there are also messages addressed to specific people and groups. We read them, either in community with those who are addressed or hoping for an example which can apply to our own lives. This can be a good thing, but we ought always to be careful about reading even the Word when it is addressed to someone else.
This was first raised to me in a group talking about Ephesians. One of the members of that group insisted that since Ephesians 5: 22-24 are addressed to wives, husbands ought not even to read those verses. The husbands have their own message in verses 25-33. Let the wives read the message addressed to the wives and let the husbands give their attention to what was written for them.
Of course, the reverse point is just as valid: Wives ought not to read verses 25-33 as if addressed to themselves. Those verses are addressed to their husbands; the wives should leave them alone. Similarly, parents ought not to focus on Ephesians 6: 1-3 but should instead be reading 6: 4, which is written to them.
The concept can be expanded to other Biblical passages. For example, when Jesus said, "Go sell everything you have," he was addressing a particular rich community leader (Matthew 19, et al.) Those of us who are not rich or not that man may not be addressed by this message. And when Jesus said, "Woe to you, scribes and Pharisees!" (Matthew 23 et al.) he was addressing specific groups of scholars in his community; the message may not apply to everyone else. We read these passages, but we ought only to read them as outside observers. We read these passages, and we should endeavor to remain outside of the story rather than to become one to whom such words are addressed.
The same thing can be said for the bloody passages in the Old Testament. If Deuteronomy (20: 16) says, "when you capture cities in the land the Lord your God is giving you, kill everyone", if is good to remember that we are reading someone else's mail. I am not one of the Hebrews recently escaped from bondage in Egypt, the kingdom God has promised to me is not located in the land of Canaan, and the commands of Jesus require me to be even better than were our spiritual ancestors. I wonder why that was the message given to these other people, but it was a message to them and not to me.
The temptation in reading other people's mail is that from this taste of extra knowledge we presume a bit of omniscience: Now that I know the color of the barn, I understand how the dairy farm should work; what's more, I will begin to instruct you how to play the dairy game. However much you read of other people's mail, in actual reality the only game you are allowed to play is your own.