" . . . Until I went into the sanctuary of God; then I understood their end."
Asaph, the writer of this Psalm, was flustered, because he couldn't understand why the wicked seemed to prosper. But, once he (Asaph) came "into the sanctuary of God" everything began to make sense. This is an important and universal principle that the Lord insists upon: until or unless we are His church, worshipping Him on His day, we can expect no illumination or understanding.
Sunday, church, and worship give form and function to our Christian lives. Let us enter God's sanctuary Lord's Day to Lord's Day, and enjoy the fulfillment that He pours out upon us there, in Christ.
[Puritan quote of the day: "Under this gracious [New] Covenant, sincerity is perfection." --Richard Sibbes, in "The Bruised Reed"]