Psalm 50:16

But to the wicked, God says:
"What right have you to recite my laws
or take my covenant on your lips?
(NIV)

Here is the shift in the passage. The main thing that I want to point out is that the rest of the passage is addressed to the wicked.

In the scriptures, especially in the Old Testament, there are two groups of people: the righteous and the wicked. Now, we are all wicked at birth, but when a person follows after God's ways and Christ's blood has cleansed him from sin, then we are considered righteous. This is not because of our own righteousness, but because of Christ's righteousness that has been imparted to us. God sees Christ's righteousness when He sees us.

Notice though that in this passage the wicked are people that are reciting God's laws and speaking His covenants. This is something that would have been taking place in a place of worship or with other believers. The point that I am trying to make, and that the passage is pointing out is that not all people who claim with their mouth are truly righteous.

There are some harsh warnings for people who are in this circumstance, but there are also some ways to tell if you are one of these people. Consider reading the book of I John. Here is some of it.