God is. He exists. He is the only self-existing one with no beginning or end. He is the eternal source, creator, sustainer and sovereign ruler of all life. He is one divine nature (being; essence) in three person unity (trinity): the Father, Son and Spirit. He is perfect with no wrong, sin or evil found in him or from him. Evil is descriptive of anything or anyone separated from and lacking relationship to God. God is holy, completely separate and distinct from all else. God is described with countless more characteristics and attributes including good, loving, truthful, just, supreme and glorious.
Example passages to reference:
Genesis 1:1, 26; Deuteronomy 6:4; Matthew 3:16-17 and 28:19; Jude 20-21