If so be ye have tasted that the Lord is gracious. Therefore, rid yourselves of all malice and all deceit, hypocrisy, envy, and slander of every kind. Like newborn babies, crave pure spiritual milk, so that by it you may grow up in your salvation, now that you have tasted that the Lord is good.
Milk is an essential part of a baby's diet.
Without milk they would die. Without spiritual milk we would die. This milk is the word of God. Physical and spiritual growth have many similarities. The same should also be true for spiritual milk.