The Supreme God is infinite; everything about Him is infinite

Human birth is best due to endowment of the special quality of power of discrimination between good and bad and eternal and non-eternal. Physical bodies are in the grip of numerous births and deaths, and are subject to many other drawbacks. This renders the physical body to being non-eternal. If this physical body is non-eternal then the body’s sense organs must also be non-eternal and whatever is perceived by non-eternal sense organs must also be non-eternal. Therefore, if there should be any eternal entity, it must exist beyond the comprehension of human material non-eternal sense organs.
    In the Mahabharata, Arjuna was blessed with divine eyes, so that he may witness the vishwarupa of Krishna, a dazzling sight. Thousands were present at Kurukshetra when Krishna revealed His Virat form, yet Arjuna was the only one to see Him like that. Why?
    The Supreme God is infinite; everything about Him is infinite. He has created countless species to a plan. If one accepts that human beings can determine their own cause by means of material senses, mind or intellect, then that will be a mentally or intellectually concocted thing. That will not be Reality. If Reality is in fact Reality, then He must always exist. What is the Truth? Why do we wish to be eternal? Why are we eager to learn and to experience bliss? We are a part of the Supreme – so we are like the Supreme in some respects. He is Sacchidananda and so are we. Sat in Sanskrit means eternal life, chit is eternal knowledge and ananda is eternal bliss. Soul is sacchidananda. We were given this limited body to know our true identity. Our duty is not to hanker after temporary bliss, but to have eternal bliss. We have to find ways to realise our true identity to become servants of Sacchidananda. Since we are part of the Supreme Lord, it is our primary task to serve Him or to act in a way that pleases Him. Once we realise Him, we will also realise other eternal truths, and know that not only He, but His Associates, too, do not take birth, but descend.

When everything arises from God, then why the gunas are not in Him

As the Gunas (modes of nature, Sattva, Rajas and Tamo) are weapons of mother Durga to capture and keep the living entity (Jiva) in this material world.
She is the confidential servant of Lord Shri Krshna (Supreme personality of God head) and she is none other than maha maya too. Her job is to tie the living entity into this material world by hook and crook. So, Lord is controller of the mother nature and he never come in contact with these three Gunas and he completely aloof from this aspect.

In the words of Srila Prabhupada

All material activities in the world are being conducted under the three modes of material nature. Although these material modes of nature are emanations from the Supreme Lord, Krshna, He is not subject to them. For instance, under the state laws one may be punished, but the king, the lawmaker, is not subject to that law. Similarly, all the modes of material nature—goodness, passion and ignorance—are emanations from the Supreme Lord Krshna, but Krshna is not subject to material nature. Therefore He is nirguna, which means that these gunas, or modes, although issuing from Him, do not affect Him. That is one of the special characteristics of Bhagavän, or the Supreme Personality of Godhead.