The following is taken from "Tell us about God, Who is He?" by the Catholic Information Service, Imprimatur Joseph Cardinal Ritter, Archbishop of St. Louis:

There are two kinds of arguments for God’s existence.  The first affirms His existence from the use of reason; and the second grows out of the historical existence of Jesus.
     The arguments from reason begin with the premise that this world does not contain its own explanation. As we know our world, it is a planet revolving about the sun, ninety-three million miles away.  The sun itself is not the center of the universe.
     At the same time there are man-made satellites revolving about the sun.  If we ask we put them there and how did they get there, the answer is that scientists put them there using rocket-stages to get them into orbit.  If another satellite went into orbit again we would ask how it got there.  We would remain unsatisfied until we discovered that the agents were the Russians or the Americans or the British.
     The same mental instinct which demands to know who has put a rocket into orbit around the earth, also demands to know who has put the earth into orbit around the sun.  To answer that the earth is just there and so is the sun leaves us dissatisfied because it offers no explanation.
     This is another way of stating that there is no effect without a cause.
     Common sense is always looking for causes to explain events.  Police find a dead man on the road. How did it happen: was it a hit-and-run driver? Did the man fall out of the car? Who is he? Who did it?
     We know when we are causing something. I drive a golf ball from the first tee.  Something happens because I make it happen.  Nothing happens without a cause.  A plane crashes and there is an investigation called because common sense assures us that nothing happens without a cause. The cause is there, even if we cannot discover it.
     What or who caused the earth? Whatever, whoever brought this vast immense universe into being cannot be less than its effect.  A man with strength to lift only half a ton cannot lift a whole ton. If he lifts a ton he must have that much muscular strength.
     We are then dealing with a Power of some sort of immensity to explain the immensity of that universe we observe.  What sort of Power can it be? Day follows night with regularity; season follows season; trees, flowers, animals all follow a certain and predictable course of behavior. What happens is so well-defined that we can say they happen according to laws in nature. The Power is a law-giver, a law-maker Who gives testimony of intelligence.
     This immense Power of terrifying Intelligence (we are still making fresh discoveries of design in nature) is subject to the same question. Who caused it or Him? If it or He is the effect of another Cause, there must be behind Him another Cause, of which He is the effect; or He must be without a Cause because He IS of Himself and not of another.  Ultimately there must be a Being That Is, a Supreme Cause Who depends upon no other for His existence. 

The Reflection of God in the world 

     We are not content with the statement that God made the universe. We ask further what is His relation to it? How is He present in the universe He has made? There are some who think that He is infinitely removed from it; and others who say that He is so much in it as to be identified with it. The first set of thinkers are so impressed by the absolute perfections of God that they think He would be diminished in some way, unless he were cut off from it. He is the architect but once the building has been made He leaves it to stand by itself.  The second group are so impressed by the world as an expression of the Divine Artistry that they think God is in the universe as the singer is in the song. The order they see in the universe is God in the universe, which, as it evolves, expresses the growth of God in perfection.
     Group one assumes that the Supreme Cause is not interested in His effects. Group two assumes that the Supreme Cause is not supreme, and in identifying Him with His creation asserts that He is not perfection, but is growing thereto.
     Midway between these two extremes is the view that God is the Supreme Cause from Whom all things ultimately proceed to their separate existence. God is thus the ground of all beings but remains the Separate One. In this view God is so perfect that He needs nothing outside Himself; yet, nevertheless, He has, out of love, produced a finite and limited world in a vast universe.
     This world is, then, an expression of the Divine Artist and, by a consideration of the things that He has made, it is possible to see a little of the Divine Imprint; in the same way we examine a portrait and determine its authorship by some great painter.
     Of all things we can ask a three-fold question. We ask—on what plan was this conceived? Some material thing, such as a flower or a dog, contains within it an idea, a blueprint, a form. We say to ourselves that the blueprint of the flower is to ensure the continuance of a plant species by the formation of seeds.
     Then we ask—why was it made in the first instance? What is its ultimate purpose? And lastly we ask—who made it?
     Consider these aspects at work in an artist.  He is, shall we say, a sculptor.  Before he chisels his stone he must have an idea of what he wants to do. Secondly he must have a purpose, an intention to carry out his plan; and lastly he must put his plan into effect. Omit any of these and no statue will be made. The final work will embody the artist—his idea, his purpose, his skill in execution. 

Wisdom

     God is embodied in His universe as the Wisdom who conceived it, as the Will Who carried out the cosmic project and as the Power Who sustains it. As Wisdom God is in the butterfly and the bird.  They are both composed of living matter, but they belong to different orders of animal creation. What makes the living matter of the one a butterfly and the living matter of the other a bird, is the different conception of animal that each enshrines. The idea or the form is a reflection in matter of the idea that exists in the mind of the Divine Artist. Every tree and every flower embodies an idea in the Divine Mind and speaks of God as a poem speaks of its author.
     The wisdom of God in creation is in its last analysis the reason why we know. When we learn, it is because we discover the forms or idea hidden in the material composition of what we study.  Unlike animals we have the X-ray power to penetrate material things and find what is in them. What is printed on this page is so many letters strung into words—material things made out of pulp and print. You the reader, take the meaning out of them. Dr. Alexis Carrell in his Reflections on Life put it this way: “all (scientific) research begins with an act of faith in the rational ordering of nature.” Unless nature made sense, it could not be studied. When we study it we learn a little of the divine ideas. 

Goodness

     God is in things secondly by His goodness.  To things He has given a purpose. Plants are green because they contain a pigment, and the pigment has the power of absorbing energy from light and using that power to bond together inorganic materials in the atmosphere and make of them sugars and starches. In this way natural food granaries are formed and upon them feed animals, and upon them we ourselves feed and maintain ourselves in existence. The plant which makes starch and the animals which feed upon it follow blindly a purpose they do not understand.
     The urge by which a plant or an animal follows the law of its nature is what we mean, then, by purpose. Man must discover his own purpose by using his reason.  That purpose, the urge of a rational nature, is to discover the truth and goodness of God.
     We discover goodness in things when we experience love for them. A man loves his automobile because it serves him, gets him around, is a delight to drive. A man loves his wife because of the goodness he finds in her.  In courting days he was discovering that goodness and feeling more and more attraction to it. At the same time he was finding out more about her—what sort of common interests they shared and so on. Eventually he decided that he wanted to unite with her in marriage. Love teaches us how good things and people are, and the more we love the more we want to be united with what we love, to possess and be possessed.  In this sense our purpose in life is to know and love God—to seek His truth and His goodness.
    Without God there is no explanation for “the rational ordering of nature”—no satisfactory explanation of our own existence. Without God there is no explanation of what we mean. We are like satellites coasting in orbit and no one fired us, like arrows speeding through the air and no bowman or archer to explain them. Where did we come from, where do we go—in a meaningless orbit, from nothingness and into nothingness without explanation? 

Power

     God is in things by His power. To Moses He said, “I am who am.”  All of us have existence, but of God it can be said simply that He exists. Our existence is partial, from moment to moment.  He possesses the whole of His existence at once.  Our existence is limited—our bodies die, we are chained to space and time, controlled to some extent by pleasure and pain.
     If nothingness ever were, then nothing would ever be.  How can something come from nothing?  Only if there is a Being Whose Being demands existence can there come from nothingness the universe that we know. All the things that are owe their being to God in the same way as the rays of the sun come from the sun.
     God then is in His world by His knowledge, by His love and by His power.  This triple action comes from a Supreme Being Who is a Spirit.  For God is not tangible and He is not visible and in Him there is nothing of material composition.  For material things can suffer change because they are composed of parts and can be taken apart.  To suffer change is itself an imperfection.  And God is perfect, otherwise He is not God. He is the Supreme Spirit Who is changeless, one and entire in His wholeness for He is not made of parts, possessing all of His Being all at once. He is greatness without limit; He is all that without beginning and without end; all that He does is likewise without beginning and without end. None of His loving and none of His knowing have vanished into the past, nor have more knowledge and more love yet to come. Past and future belong only to creatures who receive their being from moment to moment. God lives, God knows, God loves, God is in one eternal now without effort and without limit.  

 "There are only two forces now in the world, good and evil. There is no middle road to follow. The choice is given to mankind: who will be your leader: satan, Lucifer, or the Eternal Father, your Creator?" - Jesus, February 10, 1978