Question: Who may worship in the LORD's Sanctuary? Who may enter into His presence?
Answer: Ultimately, we know from the New Testament side of scripture that our righteousness comes from Jesus Christ and His death and resurrection - and then by each individual putting his/her faith in Him as Lord and Savior. As a follower of Christ we then should strive to live as Christ. We will want to follow guidelines as seen in Psalm 15 - not as a means of salvation, but as an evidence of salvation.
So.... the "Answer" as seen in Psalm 15. Very easy to follow.