In the beginning there was only God. There was nothing else. Even time and light as we know of did not exist. There was no universe, matter or other spirits.
The almighty knew everything. But knowingness or knowledge was not sufficient for this great being. He decided to experience his awesome power, goodness and wonder.
In order to experience something hot you also need to experience some cold. In order to experience some high you will also need to experience some thing low. In order to experience good you also need to experience evil. So in order to fully experience something you must also experience its opposite.
This meant the God must be became some thing he is not.
To God all things are possible except one. This one exception is that he cannot Un-god God-self.
So he came up with a brilliant plan. He created the spiritual and physical universe. Since he was all good he created evil. In a sense he is also what he is not. Since he was perfect he created imperfection. Since God was too powerful and good to experience weakness, hatred, jealousy, vengeance, anger, poverty,hunger, deception, greed, sickness and so forth, he created man. Therefore, we were are part of his grand, holy and divine plan
God experiences everything man experiences. However, because he is Almighty there are some differences. Even thought God experience these negative situations, he is too powerful to get hurt by these experiences. Like the burning bush before Moses he feels the intense heat of that fire, but he is not hurt or affected by it. The Almighty Being cannot be offended or hurt by anything.
Now since something cannot come from nothing. God became everything there is. He is One and the Infinite. He is every atom in the universe. He is all the energy there is. He is the Sun, the trees, the animals, the pile of dung, filth, light, sound. He is all the spirits there is. He is the Great Seen and Unseen. There is nothing he is not.
For the Greeks everything is between Alpha, the first alphabet, and Omega, the last alphabet. Alpha and Omega is included.
What God is reminding us when he says he is the Alpha and Omega, is that he is everything there is, was, and will be forever and ever.
Hope this helps!