Tom Nettles has a sermon (I have not listened too), but he is normally someone who may be trusted: Soul Competency and Church Purity.

Soul competency means thus that every individual is responsible to God. This principle undergirds our evangelistic appeals for repentance and faith. There are no sponsors or proxies in the relation of the individual to God (Criswell Theological Journal). As B. H. Carroll put it, "This is the first principle of New Testament law--to bring each naked soul face to face with God . . . O soul, thou art alone before God!" (B H. Carroll, Baptist and Their Doctrines). Timothy George states,

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In Book One of his Institutes of the Christian Religion, John Calvin gives a classic interpretation of the innate knowledge of God which has been implanted in all persons. He refers to it variously as "an awareness of divinity," "the seed of religion" (semen religionis), and "the worm of conscience." This natural capacity of the soul for God is the basis for the incurably religious bent of all human beings. Given the devastating effects of the Fall, however, human religiousness can only issue in idolatry and self-centeredness apart from the interposition of God's grace. From the standpoint of soteriology, then, we should speak more accurately of "soul incompetence."

Reformed and Always Reforming,