No matter how many times an opportunity arises to do something we know is not in keeping with God’s law, we are never justified in our sin. Even when God allows us to be in such a situation, we must keep our eyes on the Lord, who never changes, and on His statutes, which are sure and steadfast.
If we are trusting in circumstances, or even in the advice of friends, we are unlikely to make wise choices when we are faced with temptations. Both the miraculous circumstances David found himself in and the counsel of his friends said, “This is your chance! Kill Saul and end this running and hiding and fearing for your life!”
But David knew God and knew that God’s law said, “Thou shall not kill.” Pretty simple, straightforward rule. He knew that God had anointed Saul as King, and even though David had been chosen and anointed to replace Saul, he knew the timing and the fulfillment of that were entirely in God’s hands, not his. God does not call us to violate His commands in order to achieve His plans.
God doesn’t need us to lie to protect someone. He doesn’t approve us cheating or stealing even if it is for charity. It’s not OK for us to treat someone badly because they deserve it. Telling ourselves that the ends justifies the means is essentially suggesting that God is not able to accomplish His purposes without us violating His laws.