GENESIS 3:

The serpent deceived the woman; "For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil." she and Adam ate from the tree. The earth became cursed, and God sent Adam and Eve out of the garden.

"Notice how Satan puts a wall between holiness and happiness. He in effect says your adherence to God's standards is going to keep you from true fulfillment, true happiness, true satisfaction. If you will reject God's standards you will find happiness and satisfaction. That is Satan's strategy always. He's always saying, if you follow those rules that God gave you, it's going to ruin your life. Whereas God tells us that there is an inseparable connection between holiness and happiness, between obedience and satisfaction, between doing the will of God and receiving a blessed eternal reward. Never forget that Satan will always work against you by trying to get you to buy the lie, that holiness will keep you from happiness. The truth could not be further from that. Only in holiness do we find perfect happiness."

(J. Ligon Duncan)