I think that in some circles there’s pressure for Christian ambassadors to “close the sale” as soon as possible. When pressed for time, get right to the meat of the message. Get to the Gospel. If the person doesn’t respond, you’ve still done your part. Shake the dust off your feet and move on.
A wise ambassador, though, weighs his opportunities and adopts an appropriate strategy for each occasion. Sometimes, the simple truth of the cross is all that’s needed. The fruit is ripe for harvesting. Bump it and it falls into your basket.
Usually, though, the fruit is not ripe; the nonbeliever is simply not ready. He may not even have begun to think about Christianity. Dropping a message on him that, from his point of view, is meaningless or simply unbelievable doesn’t accomplish anything. In fact, it may be the worst thing you can do. He rejects a message he doesn’t understand and then he’s harder to reach next time.
Now here is my own more modest goal. I want to put a stone in his shoe. All I want to do is give him something worth thinking about. I want him to hobble away on a nugget of truth he can’t simply ignore because it continues to poke at him.
I think this is wise counsel. Of course we want our hearer to be saved, and we should pray toward that end. But an all-or-nothing approach to evangelism can be paralyzing for some of us. I sometimes have prayed for the first step of a response simply being a sleepless night as the person has a hard time shaking a certain truth or question.
For more on this approach by Koukl, see his excellent book, Tactics: A Game Plan for Discussing Your Christian Convictions.