"... When will you ever learn that "believing" is useless without doing what God wants you to? Faith that does not result in good deeds is not real faith." James 2:20 TLB
In 1 Samuel 15, we see where King Saul was given specific direction from God by the Prophet Samuel. Repeatedly the King did only some of what God had wanted him to do and on one occasion he went beyond his authority and stepped into doing what was not within his authority before God and man.
Does the end justify the means? Never! In the sight of God, we must be completely open with him, obedience and openess with our heavenly Father brings a great intimacy with Him.