Michael Spencer (a.k.a. The Internet Monk) agrees with Iain Murray that “the main problem in evangelism is the lack of conviction of sin.” I’ll give you part of his post, but be sure to read the whole article for context and links to Iain Murray resources:
I have not seen or sensed a general genuine conviction of sin among the non-Christians that I work with in many years. In my experience, Murray’s diagnosis is dead-on target.
In 1995, the ministry where I serve experienced an “awakening” that received some attention. It was a genuine work of the Spirit, and I have no doubt that God was at work. But I also believe that this “awakening” never reached the level of general conviction of sin, and today I would call it a “stirring” and a “drawing,” but I would be reluctant to call it much else.
I simply do not meet people who are…
1) Struck with any measure of a genuine fear of the Lord.
2) Thinking of God AT ALL in Biblical terms, especially in regard to their relationship with God.
3) Concerned with their own sinful condition as a matter of God’s wrath.
4) Convicted with a sense of sin MORE than a sense of their personal problems and felt needs. (This is universal, constant and unchanging.)
5) Any sense of the problem of sin other than the possibility of not going to heaven.
Murray is clear that conviction is based upon a knowledge of God. By that measure, conviction is almost impossible with the students under my ministry. There is an utter deadness to the subject of understanding the Biblical God or the Gospel in reference to the Biblical God. If I talk about God in reference to felt needs, relationships, marriage, sex or gender issues, the audience is with me. If I preach about “hurts” or brokenness in family relationships, I have attention and often emotional response. But if I talk about sin in reference to God and the Gospel, the unbelief is real and tangible.