Everyone starts as an infant by the care of their parents. This is until they can mature and take care of themselves. In comparison, the understanding of the word of God can be like an infant maturing into adulthood, slowly being able to discern from good and from evil.

"Anyone who live on milk being still and infant is not acquainted with the teaching about righteousness. But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil." Hebrew 5:13-14