The eternality of God is one of the (many) truths about God that is incomprehensible to God. Oh, we can understand the words and concepts, but the actuality of the truth is beyond our ability to digest. Thinking about Moses’ psalm, A. W. Tozer wrote this,
“‘From everlasting to everlasting, thou art God,’ said Moses in the Spirit. ‘From the vanishing point to the vanishing point’ would be another way to say it quite in keeping with the words as Moses used them. The mind looks backward in time till the dim past vanishes, then turns and looks into the future till thought and imagination collapse from exhaustion; and God is at both points, unaffected by either.”
From vanishing point to vanishing point, God exists.
Yet that is not all. Yes, God exists eternally, but so does everything pertaining to God. So Scripture says that the following are also eternal:
Words of Grace 