David asks the question in Psalm 15: "Who may live in God's sanctuary?"
The answer is a description of a righteous person, one who takes no bribes and speaks no evil, who honors his promises and fears God. While the Bible just made it clear in Psalm 14 that there is "no one who does good, no, not one," we know it is also possible to strive for righteousness in this life. This Psalm gives us a picture of what such a righteous life looks like. Of course, true righteousness comes only by Christ through faith in Him!