How do we know that God exists? Honestly we have no definitive proof of God’s existence. Yep, you read that right. Zip. Zero. Zilch. Nada. We have scripture that is the definitive source for believers, but if you believe the Bible, then you are already under the presumption that there is a God. What we have outside of the Bible are 4 major arguments for the existence of God. I believe that every believer should know these to better be able to defend their faith in a world with increasing unbelief in the existence of God.
I will provide you with a brief definition and presentation of each argument for the existence of God. I recommend you further research each argument for yourself to become fully equipped to present and defend your faith more thoroughly. You can also check out Wayne Grudem’s book on Systematic Theology for more a in depth look.
While it is important for believers to know scripture, I do not use scripture in the presentation of these arguments, because you cannot use scripture to someone who does not value scripture. These arguments can be used based on what many people believe and value.
Cosmological Argument –
The cosmological argument is “an argument for the existence of God based on the observation that, since every known thing in the universe has a cause, the universe itself must also have a cause, which can only be God.” “Common sense teaches us that it must be caused by a power sufficient for its rational explanation.”
This means there had to first be a reason to which the universe was made, and secondly that reason had to come from a power great enough to create it. The cosmological argument is the natural deduction of what science regularly refers to simply as cause and effect.
Or looking at it in another way, it fulfills Newton’s Third Law of physics. This states that for every action there is an equal and opposite reaction. The action therefore would be God’s speaking it into existence, and the reaction would be the creation of the universe. The ability to speak that magnitude of creation in accordance with Newton’s theory, equals the magnitude of the universe. Therefore that magnitude of power to create can only come from God.
The finite minds of humans may not be able to fully comprehend that magnitude, but nonetheless that magnitude obviously exists.
Newton’s third law in itself refutes the Big Bang theory, in that according to the big bang a simple one time occurrence happened, yet life and creation compounded on itself continuously to this day creating new life and an expanding universe. This continual progression of life, accords with an eternal God.
See also: Romans 1:20
Moral Argument –
The moral argument is “an argument for the existence of God which reasons that there must be a God who is the source of man’s sense of right and wrong.” The moral argument also points out man’s need for justice to be done, and argues there must be a God who will someday mete out justice to all people.
“This argument was first prominently presented by Immanuel Kant, who rejected the cosmological, ontological, and teleological arguments. He was convinced of man’s inescapable sense of ought, whether by conscience or obligation. He believed, the fact of a moral law and the necessity of guaranteeing both the reward and punishment of vice demand that we recognize the existence of God.”
Mankind naturally has an inner barometer that tells him that something is either right or wrong. This is why a person will proclaim injustice, prejudice, bias, or unfairness when they see it taking place. Even though the “old man” or the “flesh” as is often referred to in scripture can still sense when injustice is being done, that naturally occurring barometer becomes enhanced within believers by means of the Holy Spirit.
When a person regularly dismisses acknowledgement and alert to moral injustice, the conscience will become seared and lose sense of moral certainty.
In the ever changing and fast paced society in which man currently lives, there are an increasing number of moral grey areas that have never been traversed into before, and are not specifically lined out yet as right or wrong.
Ontological Argument –
The ontological argument is the “argument for the existence of God that begins with the idea of God as the greatest of beings that can be imagined. As such, the characteristic of existence must belong to such a being, since it is greater to exist than not to exist.”
The ontological argument also states, “the idea of God is infinitely greater than man himself. Hence it cannot have its origin in man. It can only have its origin in God Himself.” Or to put it another way all men have intuitively the idea of God, and he then tries to find proof of his existence in the idea itself.”
The ontological argument can be summed up in the idea and understanding that all men have a natural inner sense there is something greater than us at work in the universe. That inner sense then draws us to find the proof of that greater being’s presence or existence. This inner sense of God tells one there must be a reason to exist.
The fact that humanity is here is proof that it is greater to exist rather than not exist. If it is greater to not exist, we would not exist. To build upon the idea that it is greater to exist than not exist, it is deductible that we exist in this level of creation for a reason.
Humans are mindful, reasoning creations with the highest level of consciousness within creation, therefore it is natural to deduce that a supreme being, God, has created humankind, and created them for fellowship.
Teleological Argument –
The teleological argument is the “argument for the existence of God which reasons that, since the universe exhibits evidence of order and design, there must be an intelligent and purposeful God who created it to function in this way.” “The teleological argument is a sub category of the cosmological argument. It focuses on the evidence of harmony, order, and design in the universe, and argues that its design gives evidence of an intelligent purpose. The Greek word teleos means “end” or “goal” or “purpose.” Since the universe appears to be designed with a purpose, there must be an intelligent and purposeful God who created it to function this way.”
This order and design of the universe can be seen from structures on the grandest scale of planets and constellations of stars that are kept in their course by great centrifugal and centripetal forces in the universe; all the way down to the microscopic scale of atoms that display an orderly arrangement of protons, neutrons, electrons, et al.
Many scientists stand in agreement that if some of the most complex calculations of numbers such as the mass of electrons, electromagnetic forces, and/or the strength of gravity were changed by even just a single degree, we would cease to exist. This level of intricacy does not happen by random chance as suggested by some scientists. This level of broad-spectrum collaboration that is present between these intricate and delicate values point toward a designer, rather than mere happenstance.
So how can we answer the question,”How Do We Know God Exists?” While we do not have definitive proof of God’s existence, we do have faith, as well as these four major arguments the can steer us towards his existence. I pray you will study these more in depth for yourself and broaden your faith in the mean time.
 Wayne Grudem, Systematic Theology: An Introduction To Biblical Doctrine, (Grand Rapids, MI: Zondervan, 2000), 1239.
 Robert Harden, “Systematic Theology I.” Lecture, Southwestern Assemblies of God University, Waxahachie, TX. January 12, 2011, Tegrity video file, https://sagu.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=97a26a7d-ff67-4209-8a92-68102318b84f (accessed September 8, 2016).
 Grudem, 1248.
 Ibid., 143.
 Harden, slide 14.
 Harden, slide 12.
 Grudem, 1255.
 Ibid., 143.
 Harden, slide 8-9.