The concept of God is truly hard to get your mind around, isn't it. But, even though we understand very little about His total nature, the fact is that He has revealed certain aspects of Himself and continues to do so. In Old Testament times, He chose the Israelites (only He knows why) to be the people through whom He revealed His personal nature to the world. They faithfully kept the record of what He did for and through them.
Heb. 1
1 God, who at various times and in various ways spoke in time past to the fathers by the prophets,
We learn that He is stern, a righteous judge, jealous, holy, eternal, the only true God, Creator of the universe. And also that He is true, faithful, and a loving provider to those who follow Him.
Then in New Testament times, He revealed much more of His character in the person of Jesus Christ.
Heb. 1
2 has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds; 3 who being the brightness of His glory and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high, 4 having become so much better than the angels, as He has by inheritance obtained a more excellent name than they.
Now, one can look at the world, the universe, it's beauty and complexity, and reasonably come to the conclusion that it was not an accident, but God chose to make things a little bit clearer for His creation, man, speaking through the Biblical writers. On top of that, He put in all men an innate curiosity about God, a desire to know of Him. That is why even self-professed atheists converse about and are even inquisitive about God. Of course they also dismiss the concept of God as so much foolishness, the right to do so, God, in His wisdom and love, has given them. This then is another example of the immensity of God, giving men the right to refuse Him. But God also calls this man a fool, and eventually, because God has standards that have to be upheld, He will have to deal with this denial.
But God is not unreasonable about it. He has given all of us a choice.
Is. 1
18 Come now, and let us reason together,
Says the LORD,
Though your sins are like scarlet,
They shall be as white as snow;
Though they are red like crimson,
They shall be as wool.
19 If you are willing and obedient,
You shall eat the good of the land;
20 But if you refuse and rebel,
You shall be devoured by the sword;
For the mouth of the LORD has spoken.
The fact is that if you give your intellect and your doubts over to God in faith, he will in due time clear up many of the mysteries and questions that you have. He will open your eyes to those things that will help your faith in Him grow. Every Christian starts at that point. I pray that you will too.