God has revealed Himself to man. Hence, we can know God in as far as He has revealed Himself to man.
God has revealed that He is the only God. There are no other gods. He alone is God.
Because God is alone God, than He, as God, must be responsible for creating the Universe. Why? Because only a being that is outside of time could have started time, and since a god is, by definition, supernatural, than God must be above time. Time is natural, so God is above it, being super-natural. Hence, God started time and created the Universe.
But creating an Universe isn’t something light. It requires enormous power, inexhaustible power. So God’s power is infinite. But a finite being cannot have infinite power, so God Himself must be infinite. Everything of God must be infinite, therefore, so if God has an attribute, that attribute must be infinite.
There is a slight problem with infinity and infinite power, however: Consistency. A being cannot be infinite one moment, than finite the next, nor can an infinite being have anything less of infinite power. So God must be unchangeable. He must be consistant, constant.
But this brings up another problem, namely, timelessness. An infinite being requires infinite existence, and this because of its inexhaustible power. If a being did not exist at some time, than it cannot be said to have inexhaustible power, because infinite power is above time. Furthermore, time did not exist before it was created. So time could not exist before God. Hence, God must be eternal, that is, He must have always existed, and He must always exist, and His existence can never be changed. If God dose not exist now, than He is not eternal. If God will cease to exist at some time, than He is not eternal.
This brings up a third problem: How can God be omnipotent, infinite, constant, and eternal? He must have an attribute that keeps Him so. This attribute is perfection. Perfection is the state of absolute goodness, and by goodness I mean all good things: existence, truth, beauty, glory, intelligence, etc. If God is not perfect, than He must be imperfect, and so, He could be made better. But God cannot be made better if He is infinite, because there is nothing greater than infinity. So God must be perfect. Hence, He must be all-good: all-beautiful, all-truthful, all-glorious, etc.