Many messages, perhaps every message consists of more than one message. There is the message (text) and an associated message (sub-text). A simple example could be a child saying, 'Mummy, I want a hug' with the sub-text being 'Its windy outside and I feel a little bit frightened.' A more complex example could be a TV programme of the mid-evening variety, say set in a hospital or family business, which sets out to explore an issue, say, abortion (text) but the sub-text is, say, the acceptability of abortion or the right of a woman to choose without restraint of moral or family concerns.
When we preach its worth thinking about the sub-texts of our messages. Both thinking about sub-text(s) we intend to be communicated and which are good and holy and worthy things to say, and about sub-text(s) we do not actually want to communicate.
We might set out to preach about God's expectation that Christians forgive each other. Along the way we provide illustrations which encourage our hearers to forgive one another with the (good and holy and worthy) sub-text being the message that a forgiving community is likely to be an attractive community for the gospel as people see how we love one another. But we might also take care because we realise that if we tell story X we will be giving a reasonably obvious sub-text about situation Y where it is well known to the congregation that some unfinished relational business needs to be conducted!
Sometimes we might bring the sub-text right out into the open. (Perhaps it is no longer a sub-text after that)! Our church might be enmeshed in a large building project which is a little bit controversial. We are going to preach on Nehemiah rebuilding Jerusalem. So right at the beginning we acknowledge the building project, acknowledge the differences of opinion, and then launch into Nehemiah. In this kind of case, not to mention the building project and its controversy could be to make members of the congregation feel that they are being subtley got at - that the message we were really bringing was not about Nehemiah but about the situation at our church. The problem with the sub-text then is it is likely to get people's backs up and they will fume way at the sub-text while the text - the message about Nehemiah sails over their heads!