The existence of God shall be proven through reason and faith.

A. The proof of reason shall consist of

1. The cosmological fact.
2. The ontological fact.
3. The teleological fact.

Sections 2—6 cover the proof of reason.

B. The proof of faith shall consist of

1. Scripture.
2. Tradition.
3. Knowability.

Sections 7—12 cover the proof of faith.

Cosmological Proof. God is proven by the cosmological fact, which states that—

• it is impossible according to the laws of human thought to give any ultimate rational explanation of the phenomena of external experience and of internal consciousness —
  • in other words to synthesize the data which the actual universe as a whole supplies (and this is the recognized aim of philosophy) —
• unless by admitting the existence of a self-sufficient and self-explanatory cause or ground of being and activity,
• to which all these phenomena may be ultimately referred.

Enforcing the Proof. To enforce this cosmological fact, it shall be established—

• the general argument proving the self-existence of a First Cause,
• the special arguments proving the existence of an intelligent Designer and
• of a Supreme Moral Ruler, and
• the confirmatory argument from the general Consent of mankind.

Cosmological Proof in Full.

A. Principle of Causality. The principle of causality shall be established, which states that—

• whatever exists or happens must have a sufficient reason for its existence or occurrence either in itself or in something else;
• in other words whatever does not exist of absolute necessity -
  • whatever is not self-existent —
• cannot exist without a proportionate cause external to itself.

B. Causal and Cosmological Facts.

1 — First Cause.

• Motion, i.e. the passing from power to act, as it takes place in the universe implies a first unmoved Mover, who is God; else we should postulate an infinite series of movers, which is inconceivable.
• For the same reason efficient causes, as we see them operating in this world, imply the existence of a First Cause that is uncaused, i.e. that possesses in itself the sufficient reason for its existence; and this is God.
• The fact that contingent beings exist, i.e. beings whose non-existence is recognized as possible, implies the existence of a necessary being, who is God.
• The graduated perfections of being actually existing in the universe can be understood only by comparison with an absolute standard that is also actual, i.e., an infinitely perfect Being such as God.

2 — Intelligent Designer.

• The wonderful order or evidence of intelligent design which the universe exhibits implies the existence of a supramundane Designer, who is no other than God Himself.
  • from the existence and perception of beauty in the universe (the aesthetical argument), a supreme Designer who gives form to beauty shall be construed to be present.
• Spirituality, i.e. intelligence and free will, shall be attributed to the First Cause, in other words by recognizing a personal God, for the cause in all cases must be proportionate to the effect, i.e. must contain somehow in itself every perfection of being that is realized in the effect.

3 — Supreme Moral Ruler.

• The internal witness of conscience to the supremacy of the moral law, and, therefore, to the existence of a supreme Lawgiver (this may be called the ethical argument)

4 — General Consent of Mankind.

• Mankind as a whole has at all times and everywhere believed and continues to believe in the existence of some superior being or beings on whom the material world and man himself are dependent, and this fact cannot be accounted for except by admitting that this belief is true or at least contains a germ of truth.

Ontological Proof. The existence of God may also be demonstrated ontologically, which states that—

• the idea of God as the Infinite means the greatest Being that can be thought of,
• but unless actual existence outside the mind is included in this idea, God would not be the greatest conceivable Being
• since a Being that exists both in the mind as an object of thought, and outside the mind or objectively, would be greater than a Being that exists in the mind only;
• therefore God exists not only in the mind but outside of it.

Teleological Proof. God gives every person a supernatural calling to seek Him across creation; God is the end or underlying source of all happiness and glory men seek to obtain through their earthly conduct, which states that—

• Man’s desire to know, to achieve, and to order the world, are all a result of his supernatural urge to come to know God across all the works of His creation, and to act legitimately on His behalf.
• Hence the reason he seeks to know the basis of life, like the philosopher, to intelligently and beautifully order the world, as the politician or statesman, and to act rightly and admirably, as the father or mother, or the brother or sister or son or daughter.
• All this is the result of the desire he has been supernaturally endowed with to know God, and the prima facie knowledge man has that an omnipotent, all intelligent and all good God exists for Him to receive and attain communion with and from.
• The existence of this supernatural urge showcases the One who wisely and personally put it there.

Gift of intellect and free will. God has granted man his free will and intellect. Genesis 2:26-27 states—

Let us make human beings in our image, after our likeness...

God created mankind in his image;
    in the image of God he created them;
    male and female he created them.

Divine Recognition of Light. God knows he can moreover be recognized through the light of free will and intellect across creation. God has endowed men with the faculty to use it wisely, to witness Him. Wis., xiii, 1 states:

• But all men are vain in whom there is not the knowledge of God: and who by these good things that are seen, could not understand him that is, neither by attending to the works have acknowledged who was the workman.

Only the fool denies the existence of God in his heart (Psalm 13:1).

Right Application of Human Reason and Will. In the verse from the previous section it is clearly said—

• that the phenomenal or contingent world — the things that are seen — requires a cause distinct from and greater than itself or any of its elements;
• that this cause who is God is not unknowable, but is known with certainty not only to exist but to possess in Himself, in a higher degree, whatever beauty, strength, or other perfections are realized in His works,
• that this conclusion is attainable by the right exercise of human reason, without reference to supernatural revelation, and that philosophers, therefore, who are able to interpret the world philosophically, are inexcusable for their ignorance of the true God, their failure, it is implied, being due rather to lack of good will than to the incapacity of the human mind.

Supernatural Calling and Communion. God supernaturally calls all men to him and offers heavenly communion to them. In Luke 8:21, Jesus says, "Blessed...are those who hear the Word of God and obey it."

Holy Seat Teaching. God is known with certainty. The Holy Seat teaches—

• that God, the first cause and last end of all things, can, from created things, be known with certainty by the natural light of human reason.

Moreover, God, the beginning and the end, as the Creator, can be known with certainty by the supernatural light of the human will, through faith.

Light of Reason and Faith and Proof. God is proven. Certain knowledge of God is declared to be attainable "by the light of reason", i.e. of the reasoning faculty as such from or through "the things that are made"; and this is inferential proof.

By a similar nature God is proven by the light of faith, of the faculty of will, by assenting through divine vocation to the infinite constitution of God. The will thus makes communion from or through the actions of the Maker. For at that point God enlightens the heart of man personally.