Laidlaw was a Free Church of Scotland minister, professor and theologian that later joined the United Free Church of Scotland in 1900. His The Bible Doctrine of Man is a standard conservative work in the field.
The Bible Doctrine of Man, 1879, revised 1895, reprinted 2005 by Tentmaker
Ch. 11, ‘Sin in the Race and in the Individual’
Once more, let us observe that while the Scripture statement is so strong in asserting a corruption of man’s whole nature, and in assigning that corruption to the center and fountain of his moral life, and while the force of that statement is vainly sought to be evaded or softened down, yet the Scripture asserts no corruption, depravation, or destruction of his natures, faculties, or powers as such. It recognizes a constitution which, in relation to the end for which man was made, is wholly gone wrong, and has no power to right itself. But this just strength of statement is entirely misapplied when the Scripture language is transferred literally to the wholly different region of human psychology, and the powers of the soul are held to be corrupted as powers and faculties. The great Protestant theologians have always perceived this, and have accordingly repressed as unscriptural all such extremes. They have usually repelled the error by saying that, while man since the Fall can do no good in any divine relation, his natural and civil actions may be correct and virtuous. Not only so, but maintaining the validity of man’s natural faculties and of their operation on natural things,—the denial of which would be a universal pyrrhonism [a school of skepticism from Pyrrho †270 BC, that majored on the fallibleness of human senses and faculties],—it has been an essential of the evangelical theology to maintain, further, that there is possible to fallen man a natural knowledge of God, and even a natural acquaintance with truth supernaturally revealed, as contrasted with a spiritual and saving knowledge of God and things divine. This position was strongly contended for by the orthodox theologians of the seventeenth century in opposition to the Socinians, who denied it. Its value consists in its forming the proper foundation of natural theology, as well as in its being an essential part of the Scripture doctrine of the divine image.
The Scripture view of the Fall, as we have seen, is that it was radical and fatal as regards man’s relation to God. The consistency of this with the maintenance of validity in fallen man’s natural faculties, and of the goodness of his actions in a natural sense, is sometimes stated in this form, namely, that it is the constitutional working of man in his moral and religious life that is vitiated by sin, but not his parts and faculties…