Perhaps the best way in which I can stimulate thought, and give some little help in this matter, is to make the blunt statement that I have not followed this practice in my ministry (to give altar calls). And let me give some of the reasons which have influenced me in that respect. I shall not attempt to state them in any exact systematic order, but here is roughly the order. The first is that it is wrong, surely, to put direct pressure on the will. Let me explain that. Man consists of mind, affections and will; and my contention is that you should not put direct pressure on the will. The will should always be approached primarily through the mind, the intellect, and then through the affections. The action of the will should be determined by those influences. My scriptural warrant for saying that is Paul's Epistle to the Romans chapter 6, verse 17, where the Apostle says: 'God be thanked that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine that was delivered you.'
D. Martin Lloyd Jones, pg. 271, Preaching and Preachers