Jesus also presents scary truths like this in His teachings. He said things like:

Mat 7:21-23 (NIV) Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only he who DOES the will of My Father Who is in heaven.

Many will say to Me on that day, ‘Lord, Lord, did WE not prophesy in Your name, and in Your name drive out demons and perform many miracles?’ Then I will tell them plainly, ‘I never knew you. Away from Me, you evildoers!’

Immediately after this Jesus starts talking about the difference between those who hear His words and those who hear His words and do them.

Mat 7:24 (NIV) Therefore everyone who hears these words of mine and puts them into practice is like a wise man who built his house on the rock.

Luke 6:46 (NIV) Why do you call Me, ‘Lord, Lord,’ and do not do WHAT I SAY?