Pastor spoke of the holiness of God. That our sin only corrupts and pollutes so all that we are is unholy and unrighteous. Note that the Psalm can be broken comfortably by the "Our Lord is Holy" as that is the chief characteristic of our God. This leads to Calvin's Dilemma: the sinner can either run from the Presence of the Holy God (Cain) or run to Him and fall at the feet (footstool) and beg for mercy. Moses, Aaron and Samuel called upon the Name (Holy) of the Lord but were not granted forgiveness just on this Sinner's Call. Rather they all came with Sacrifice of Blood Atonement. The unholy and unrighteous sinner can only come into the Presence of God with Blood for Atonement of sin. And so we come into His Presence, we call upon the Name of the Lord, by faith in Jesus Christ. He is our Priest and Lamb of Atonement (Heb 9). We too enter into the worship of the Holy One by faith in the Sacrifice of Christ for our sins.
The application was to worship the Lord God and to obey God's original intent for man: Be Holy even as I am Holy.