fundamental theology; apologetics
The science which demonstrates that God has granted a supernatural revelation and has established a Church to be the custodian and interpreter of this revelation.
As a science, it stands midway between philosophy and theology.
Man's duty of conforming his belief and conduct to whatever revealed teaching his Creator may see fit to grant is a duty evident from merely philosophical reasoning.
With this principle valid, fundamental theology goes on to prove from natural reason the twofold fact of supernatural revelation actually granted and of an authoritative interpreter permanently established.
So far it may be said to be an amplification of philosophy, since it continues to use as its principle of assent the lumen rotionis (light of reason).
The name fundamental theology is employed because the twofold demonstration just noted prepares the way for the lumen fidei (light of faith), for the acceptance, that is to say, on the part of men of good will of revelation's content.
This content is, of course, the very subject matter of theology.
The true concept of revelation, so regrettably obscured by higher critics and liberal Protestants and modernists, must be insisted on by the Catholic apologete.
Revelation is neither the manifestation of God contained in the works of creation, nor any religious consciousness, individual or collective, but is the Creator speaking to His creature and proposing religious truth to be believed on Divine authority.
What means God may use thus to speak to man, what utility there is in the communication, how man is to judge between genuine and spurious revelation, these are questions that next demand satisfactory answers.
The questions answered, the apologete addresses himself to the demonstratio Christiana, the demonstration that Jesus Christ claimed and proved Himself to be a legate sent by God to teach a doctrine of salvation obligatory on all men.
In the course of this demonstration the four Gospels are used merely as historical documents, in which we read what Jesus Christ explicitly claimed to be, what doctrines He taught, what Divine credentials (working of miracles, uttering and fulfilling of prophecies) He presented in proof of His claim.
The demonstratio Christiana culminates in the stupendous and irrefutable argument of the Resurrection.
The purpose of the demonstratio Catholica is to prove that Christ founded a Church to be the depositary and interpreter of Divine revelation, the dispenser of the means of salvation, the ruler of man's conduct.
All this is shown from Christ's own words and defended against those Christians who deny that Christ entrusted the continuance of His mission to an organized society.
What its Founder's intention is as to the constitution of the Church, next demands attention.
That this constitution is not democratic, but hierarchical, with bishops and priests to rule the faithful, and monarchical, with the plenitude of jurisdictional power possessed by one head, is proved scripturally as well as from the testimony of authentic tradition.
Now the next step of the apologete and the next enquiry of the sincere seeker of truth is the identification of Christ's Church among the many Churches that profess to be such.
The identification is effected by means of four notes or characteristics; which are Apostolicity, Unity, Sanctity, Universality.
Tracing its origin to the very age of Christ's own Apostles, one throughout its history in doctrine and government, holy extensively in the lives of evangelical virtue of a great many of its members as well as intensively in the extraordinary sanctity of a notable number, universal in being the Church not of particular polity or region, but of every nation under heaven, the true Church must stand revealed as the City of God seated upon the mountain.
A calm application of the test of the four notes shows that the Roman Catholic Church alone possesses them.
This is the final conclusion of the demonstratio Catholica or second part of fundamental theology.
New Catholic Dictionary