When Packer uses the word "should" in the following, he means it in the sense of "would."
"If we regarded it as our job, not simply to present Christ, but actually to produce converts--to evangelize, not only faithfully, but also successfully--our approach to evangelism would become pragmatic and calculating. We should conclude that our basic equipment, both for personal dealing and for public preaching, must be twofold. We must have, not merely a clear grasp of the meaning and application of the gospel, but also an irresistible technique for inducing a response. We should, therefore, make it our business to try and develop such a technique. And we should evaluate all evangelism, our own and other people's, by the criterion, not only of the message preached, but also of visible results. If our own efforts were not bearing fruit, we should conclude that our technique still needed improving. If they were bearing fruit, we should conclude that this justified the technique we had been using. We should regard evangelism as an activity involving a battle of wills between ourselves and those to whom we go, a battle in which victory depends on our firing off a heavy enough barrage of calculated effects. Thus our philosophy of evangelism would become terrifyingly similar to the philosophy of brainwashing. And we would no longer be able to argue, when such a similarity is asserted to be a fact, that this is not a proper conception of evangelism. For it would be a proper conception of evangelism, if the production of converts was really our responsibility."
J. I. Packer, from EVANGELISM AND THE SOVERIEGNTY OF GOD