Who Created God?
This question is not answerable from a Christian perspective; it presupposes God was created, but the Bible clearly teaches that God is eternal (in the truest sense of the word). An eternal being has no creator, no beginning, no end, and no cause. Rather he is the creator of all that is, the beginning and the end of all that is, and the cause of all that is.
Note, don’t confuse eternal (having no beginning or end) with everlasting (just having no end). An eternal being is literally timeless, whereas an everlasting being exists in time and lasts from it’s inception forever. An eternal being is everlasting, but an everlasting being is not necessarily eternal. Only God is eternal, though Christians will be raised to everlasting life in Christ.
Also that when the Bible speaks of eternal life, it means the life that comes from Christ, which is itself eternal as Christ is; it is not speaking of those of us who receive this life somehow becoming eternal, per se.
For reference, Biblical teaching of God’s eternal nature:
Abraham planted a tamarisk tree in Beersheba, and there he called on the name of the LORD, the Eternal God.
The eternal God is your refuge, and underneath are the everlasting arms. He will drive out your enemies before you, saying, ‘Destroy them!’
The fear of the LORD is the beginning of wisdom; all who follow his precepts have good understanding. To him belongs eternal praise.
Your word, LORD, is eternal; it stands firm in the heavens.
All your words are true; all your righteous laws are eternal.
Trust in the LORD forever, for the LORD, the LORD himself, is the Rock eternal.