From the Shorter Catechism

Q. 4. What is God?

A. God is a Spirit, infinite, eternal, and unchangeable, in his being, wisdom, power, holiness, justice, goodness, and truth. John 4:24; Job 11:7-9; Ps. 90:2; Jas. 1:17; Ex. 3:14; Ps. 147:5; Rev. 4:8; Rev. 15:4; Ex. 34:6-7.