Part I: Questions about God, Man, and Sin
12. Q. Does God know all things?
A. Yes. Nothing can be hidden from God.
(Click through to read scriptural proofs.)
And you, Solomon my son, know the God of your father and serve him with a whole heart and with a willing mind, for the Lord searches all hearts and understands every plan and thought. If you seek him, he will be found by you, but if you forsake him, he will cast you off forever.
For the eyes of the Lord run to and fro throughout the whole earth, to give strong support to those whose heart is blameless toward him. You have done foolishly in this, for from now on you will have wars.
Are not five sparrows sold for two pennies? And not one of them is forgotten before God. 7 Why, even the hairs of your head are all numbered. Fear not; you are of more value than many sparrows.
…on that day when, according to my gospel, God judges the secrets of men by Christ Jesus.
Scripture quoted from the English Standard Version.
Taken from A Catechism for Girls and Boys found here.