A type of preaching that is sometimes, indeed very frequently today, regarded as non-theological is evangelistic preaching. I well remember how when an evangelistic campaign was being held in London a few years ago, one of the liberal religious weeklies supporting the campaign said, ‘Let us have a theological truce while the campaign is on.’ It went on to say that after the campaign we must then think things out and become theological. The idea was that evangelism is non-theological, and to introduce theology at that stage is wrong. You ‘bring people to Christ’ as they put it; and then you teach them the truth. It is only subsequently that theology comes in.
I would be prepared to argue that in many ways evangelistic preaching should be more, rather than less theological, than any other, and for this good reason. Why is it that you call people to repent? Why do you call them to believe the gospel? You cannot deal properly with repentance without dealing with the doctrine of man, the doctrine of the Fall, the doctrine of sin and the wrath of God against sin. The when you call men to come to Christ and to give themselves to Him, how can you do so without knowing who He is, and on what grounds you invited them to come to Him, and so on. In other words it is all highly theological. Evangelism which is not theological is not evangelism in any true sense. It may be a calling for decisions, it may be a calling on people to come to religion, or to live a better kind of life, or the offering of some psychological benefits; but it cannot by any definition be considered be regarded as Christian evangelism, because there is no true reason for what you are doing apart from these great theological principles. I assert therefore that every type of preaching must be theological, including evangelistic preaching.
– D. Martyn Lloyd-Jones, Preachers and Preaching, p. 65.