Why do we need to be reminded of Bible truths repeatedly?
Because of our human makeup, Bible truths do not become settled in us quickly; they take a long time to get socked in. People tend to assume once something is said they have grasped it, but that is not how it works. Therefore these truths must be repeated and brought back to mind from time to time.
Les explains that even after speaking to hundreds of people, he is constantly reminded that you cannot repeat these things often enough. He says he hates to repeat because he feels that once he has said it, people have it, but it just doesn't work that way. This is part of our human makeup: it takes a long time for these things to get socked in, so we have to be reminded of them from time to time. In the same context, he points back to Genesis 3:15, where after the fall God immediately comes back with hope for the race, the promise of a Redeemer, putting enmity between Satan and the woman and between his seed and her seed.