How Do You Know that God Exists?
I believe God exists simply by looking at the marvels of the things in the universe. The Bible appeals to God’s creation as proof of His existence. No one would believe that a watch would fall into place all by itself; yet many people choose to believe that the universe, which is far more intricate, came about by chance.
The wonders of the universe
Romans 1:20 For since the creation of the world God's invisible qualities his eternal power and divine nature have been clearly seen, being understood from what has been made, so that men are without excuse.
Some scientists, who do not believe that there is a God, previously believed that the universe had always existed. Scientists later discovered that objects in the universe are moving away from each other at top speeds and the universe began in a fantastic explosion called the Big Bang. In other words, the universe had a beginning and did not exist from eternity. The Bible tells us "In the beginning God created the heavens and the earth." (Genesis 1:1)
We use the word cosmos to refer the universe because this word means orderly universe. The universe is indeed orderly! If the laws of the universe were just slightly different, life could not exist. For example, if the Earth were smaller, an atmosphere would not be possible (like Mercury and the moon) and life would be non-existent. If it were bigger, the atmosphere would contain free hydrogen (like Jupiter and Saturn) and life would also not be possible. Its distance from the sun has also to be just right - even a small change would make it too hot or too cold. The Earth is also tilted at 23o. If the Earth is not tilted, the poles would be much colder and the equator much hotter and only half the land on earth could be lived on, and many kinds of plants and animals would die. The universe is an intricately complicated design. How could it just happen without an intelligent maker?
The formation of life
What about life? How did man come about? The theory of evolution wants us to believe that life first started from non-living chemical substances which developed into living single-celled organism which in turn evolved into plants, fishes and insects, later amphibians and reptiles, then birds and mammals and finally man. But the chance that life can start from non-living matter is almost nil and countless experiments have failed to prove that it is possible. Also, if as evolution suggests, plants evolve to fishes to insects, etc, then where are all the in-betweens? Man has found fossil records of man and apes, but where are the man-ape, the bird-mammal, etc. Isn't it more logical that life came into existence by the hand of the Creator who created each specie?
The wonders of the human body
King David said in Psalms 139:14 "I praise you because I am fearfully and wonderfully made.". No one would imagine that a well designed house came about totally by chance, without a maker. Yet there are people who refuse to admit that the human body has an intelligent creator. Yet our body is one of the best-designed objects in the universe. An adult has about 75,000 miles of blood vessels neatly packed in his body. This is three times the distance round the Earth. In a normal lifetime, the little organ the size of your fist - the heart - has the ability to pump about 450,000 tons of blood. The lung weighs only a pound. Yet it contains millions of air sacs to absorb the oxygen we take in. If the air sacs are spread out, it covers an area the size of a football field! Our brain is far more complex than the most sophisticated computer systems. That little three-pound brain contains as many as 30 billion cells. Many of the tasks that the computer struggles with - image recognition, voice recognition - are handled by humans automatically, with ease.
Some people say that they do not have enough faith to believe in the existence of God. But if these people would look at the facts around them, it takes greater faith not to believe in the existence of God.
I believe that God exists because too many things are unexplainable without God. Even if I am not 100% sure that He exists, it is safer to live my life based on the assumption that He exists rather than on the assumption that He doesn't. What if I die and realize that God did exist but I have not acknowledged Him in my lifetime. How terrible would be the consequences! What if I die and find out God does not exist? I would still have lived a full and meaningful life. The choice is yours.