I'll explain further: if a deity tells you something is moral, is that truly moral? Which philosophers have touched on that specific topic?
Quite a number have done so, and there is a revived interest in the topic. You might try :
Daniel M. Johnson, 'The Objectivity of Obligations in Divine Motivation Theory', The Journal of Religious Ethics, Vol. 40, No. 3 (September 2012), pp. 504-517
Thomas M. Osborne Jr., 'Ockham as a Divine-Command Theorist', Religious Studies, Vol. 41, No. 1 (Mar., 2005), pp. 1-22.
C. Stephen Evans, Kierkegaard's Ethic of Love: Divine Commands and Moral Requirements. Oxford: Oxford University Press, 2004.
Mark Murphy, An Essay on Divine Authority. Ithaca, N.Y.: Cornell University Press, 2002
John Hare, God's Call: Moral Realism, God's Commands, and Human Autonomy. Grand Rapids, Mich.: Eerdmans, 2001
Richard J. Mouw, The God Who Commands (Notre Dame: University of Notre Dame Press, 1990.
Philip L. Quinn, "An Argument for Divine Command Ethics," Christian Theism and the Problems of Philosophy, ed. M. Beaty (Notre Dame: University of Notre Dame Press, 1990).
Edward R. Wierenga, The Nature of God, God (Ithaca and London: Cornell University Press, 1989
Philip L. Quinn, "Divine Command Ethics: A Causal Theory," Divine Command Morality: Historical and Contemporary Readings, ed. Janine M. Idziak (New York and Toronto: Edwin Mellen Press, 1979).
Philip L. Quinn, Divine Commands and Moral Requirements (Oxford: Clarendon Press, 1978).
Baruch A. Brody, "Morality and Religion Reconsidered," Readings in the Philosophy of Religion, ed. B. A. Brody (Englewood Cliffs: Prentice-Hall, 1974).
Alvin Plantinga, God, Freedom, and Evil (New York: Harper & Row, 1974.
With any luck you'll find useful material here.