We baptize our babies and train them unto the knowledge of the Lord that He promised in this new covenant.

Do not imitate faith in Christ with hypocritical, temporary faith. But imitate those who through genuine faith inherit the promises.

If you are stuck in spiritual infancy, then you must be weaned.

So a “root of bitterness” is not an attitude, but a person who is presumptuous and flatters themselves in their sin, one who hears the word of God but shrugs it off as inapplicable to him or herself.