In order to know God and respond to His good news of rescue (the gospel), we need to go straight to Scripture as our primary source for knowing God’s truth. Your children need the same thing. Start with a Bible on their level so that they can begin to know God’s truth for themselves and see God clearly as He reveals Himself through Scripture.
Bibles + Study Resources
Other Sources and Devotionals
Books such as devotionals and church history are useful as a secondary resource after your primary time spent directly in a Bible!