Answer
God's infinity is an attribute of God typically applied to him by systematicians. You won't find the word infinity in the Bible, but what the term is attempting to capture is the idea that God is without limits, that he cannot be circumscribed by space or by time, but he's of a completely different order, if you like, to the created universe.
Answer by Dr. Carl R. Trueman
Dr. Carl R. Trueman is Professor of Biblical and Religious Studies at Grove City College and formerly served on the faculty of Westminster Theological Seminary in Pennsylvania.