"But he refused and said to his master's wife, 'Look, my master does not know what is with me in the house, and he has committed all that he has to my hand. There is no one greater in this house than I, nor has he kept back anything from me but you, because you are his wife. How then can I do this great wickedness, and sin against God?'" (Genesis 39:8,9).
THERE ARE MANY REASONS TO ABSTAIN FROM SIN, BUT THE MOST IMPORTANT IS SIMPLY THE THOUGHT THAT SIN IS AN OFFENSE AGAINST THE GOODNESS OF GOD HIMSELF. Although we injure ourselves greatly when we sin, that is not the worst thing about it. Sin is an issue that has much more to do with God than with us. And just as the love of God is the most powerful reason for doing right, it is also the main thing that should keep us from doing wrong.
After committing adultery with Bathsheba and then murdering her husband, David expressed his sin in these words: "Against You, You only, have I sinned, and done this evil in Your sight; that You may be found just when You speak, and blameless when You judge" (Psalm 51:4). Surely, many people were hurt by David's transgression, including David himself. But compared to the wrong done to God, all of these wrongs were as nothing.
In spiritual matters, deciding to take God seriously is the most effective precaution we can take. If we love God as unselfishly as we should, we'll hold His honor more dear than our own, and that sense of honor will defend us and protect us from doing anything that would detract from His glory. Loving reverence is always the ultimate prophylaxis against evil. The willpower we need can only come from a combination of love and respect for God Himself.
This was clearly true in Joseph's case. When he was being seduced by his master's wife, there would have been any number of pragmatic reasons to refuse her advances. Had he been so foolish as to yield, he would have jeopardized nearly every aspect of the good life he had begun to build for himself in Egypt. Yet all of these considerations put together did not weigh as heavily in his thinking as the single factor that mattered most: God's honor. Whatever else might have been said, Joseph showed that he understood the crux of the matter when he said, "How then can I do this great wickedness, and sin against God?"
"Sin is the dare of God's justice, the rape of his mercy, the jeer of his patience, the slight of his power, and the contempt of his love" (John Bunyan).