Etymologically considered, the term theology may be defined as "the Word concerning God" (λόγος περὶ θεοῦ). In the subjective sense the term denotes the knowledge of God (Gottesgelahrtheit) as it inheres in the theologian; in its objective sense it designates the doctrine concerning God as it is presented in a book or treatise. (Cp. the meaning of psychology, physiology, biology, geology, etc.) Thomas Aquinas summarizes the meaning and function of theology as follows: "Theologia a Deo docetur, Deum docet et ad Deum ducit." The name God in connection with λόγος, however, always denotes the object, so that theology in its objective sense is properly the doctrine which teaches God (Deum docet).
The term theology in its common significance (usus loquendi) does not occur in Holy Scripture. It is therefore a "vox non ἀντίγραφος, sed ἄγραφος, quamvis non ἀντίγραφος" that is to say, a term used not in, but outside Scripture, yet one that is not against Scripture. The heading of St. John's Revelation, 'Αποκάλυψις Ἰωάννου τοῦ θεολόγου, as Gerhard correctly points out, was not selected by the author of that book, but was added by later copyists. This fact proves that the term theology was widely used already by the earliest Christian writers and was quite generally understood also in its specific meaning. However, the term theology was used also by non-Christian authors, and this fact must not surprise us, since man by nature has a certain knowledge of God, the divine Law being inscribed in his heart, Rom. 1 and 2. Pagan writers applied the term theology to the doctrine of God as this was taught by their poets and philosophers, whom some styled theologians. Thus Aristotle says of Thales and of the philosophers before Thales, who speculated on the origin of things, that they theologized (θεολογήσαντες). Cicero declares expressly: "Principia loves tres numerant, qui THEOLOGI nominantur." (Cp. Aristotle, Meta ph., I, 3; Cicero, De Natura Deorum, III, 21.)
Nevertheless the term theology has not always been used in the same sense. This varying use of the term need not give us any concern since the word itself does not occur in Holy Scripture and may therefore be employed in sacred theology in different significations, as long as it is not made to represent something that in itself is condemned by God's Word. The concepts which it is made to express should themselves be Scriptural. The term is used correctly and in accordance with Holy Scripture if it denotes -
As the term is applied generally, it denotes in its abstract sense, or objectively, either the entire Christian doctrine (usus generalis) or the particular doctrine concerning God (usus specialis).
If the term theology is employed in the above significations, it is used in conformity with Holy Scripture and therefore correctly. But if it is applied to any doctrine that goes beyond Scripture or to a system of doctrine that is not exclusively based on Scripture, but rather on "Christian consciousness," "Christian experience," "Christian tradition," etc., it is misapplied. For whatever is not drawn from Scripture is not theology at all, but human speculation, and that after all is nothing else than error and delusion, 1 Tim. 6, 3. 4: "knowing nothing."
In this treatise we use the term theology both subjectively, or concretely, to denote the spiritual ability (ἱκανότης, habitus) to teach and defend the Word of God, in short, to administer the functions of the Christian ministry in the true Scriptural manner (2 Cor. 3, 5. 6), and objectively, or abstractly, for the Christian doctrine, either in whole or in part, presented either orally or in writing, 2 Tim. 1, 13. Both uses are Scriptural. Subjective, or concrete, theology is the spiritual habitude of the Christian teacher; objective, or abstract, theology is the product, or result, of this ability. Also, we hold that the first meaning of the term is the primary, since theology must first be found in the soul of a person before that person can teach and present it either by word or in writing. If we call the product of the inherent ability theology, this is done by way of metonymy, the effect being named after the cause. For the Christian theologian this distinction is of paramount importance because it constantly reminds him that studying theology means not simply the intellectual apprehension of a number of facts, but the true regeneration, conversion, and sanctification of his own heart, from which his whole ministerial service must flow.
Dr. A. L. Graebner, in his Outlines of Doctrinal Theology (p. 1), defines theology in its subjective, or concrete, sense as follows: "Theology is a practical habitude of the mind, comprising the knowledge and acceptance of divine truth, together with an aptitude to instruct others toward such knowledge and acceptance and to defend such truth against its adversaries." Theology in its objective, or abstract, sense he defines (p. 2) as "an oral or written exhibition of the truths, doctrines, principles, etc., by virtue of the knowledge, acceptance, maintenance, and practical application of which a theologian is a theologian."
7. THE CHRISTIAN RELIGION AND CHRISTIAN THEOLOGY
Someone say that the Christian religion in its subjective sense is the knowledge of God which is possessed by every Christian believer, while Christian theology in its subjective sense is the knowledge of God which is possessed by the official teachers of the Church.
9. THEOLOGY FURTHER CONSIDERED AS A HABITUDE.
Theology as a habitude, or ability, is described in all those Scripture-passages which depict the character of the true Christian ...