The transition from theology to anthropology, that is, from the study of God to the study of man, is a natural one. Man is not only the crown of creation, but also the object of God’s special care. And God’s revelation in Scripture is a revelation that is not only given to man, but also a revelation in which man is vitally concerned. It is not a revelation of God in the abstract, but a revelation of God in relation to His creatures and, particularly, in relation to man. It is a record of God’s dealings with the human race and, especially, a revelation of the redemption which God has prepared for, and for which He seeks to prepare, man. This accounts for the fact that man occupies a place of central importance in Scripture, and that the knowledge of man in relation to God is essential to its proper understanding. The doctrine of man must follow immediately after the doctrine of God, since knowledge of it is presupposed in all the following loci of dogmatics.
We should not confuse the present subject of study with general anthropology (or, the science of mankind), which includes all those sciences which have man as the object of study. These sciences concern themselves with the origin and history of mankind, with the physiological structure and the psychical characteristics of man in general and of the various races of mankind in particular, with their ethnological, linguistic, cultural, and religious development, and so on. Theological anthropology is concerned only with what the Bible says respecting man and the relation in which he stands, and should stand, to God. It recognizes Scripture, only, as its source, and reads the teachings of human experience in the light of God’s Word.
From: Systematic Theology by Louis Berkhof (Grand Rapids: William B. Eerdmans Publishing Company, 1938), p. 181 (slightly edited)