No command of God’s is immoral.
The response that God as the Creator and “owner” in some sense of all life can use people as instruments to bring others to himself is interesting and not one I’ve considered before. However, the above response (which borders on tautology) is the right answer.
God isn’t good because we’re extraordinarily lucky to have a loving and merciful God rather than a wrathful one. God is good because He
defines what it means to be ‘good.’ Our ideas of what is good are subsequent to God’s creation and ordering of the Universe in such a way as to align with His nature. We have a sense of right and wrong which align with God’s law because he gave us this sense. This is the Natural Law.
In this sense, God cannot command something which is immoral, because whatever God does defines morality. The Christian understanding of God is of an eternal, unchanging God. His Will is entirely consistent with itself through time and space (although our perception of it isn’t–hence the apparent differences between the God of Abraham and the God of Jesus).
This is one place where our Muslim brothers stray from a correct conception of God. Allah isn’t bound by any requirements to be consistent and can literally do anything that strikes his fancy. A pious Muslim would probably agree with my reasoning in the 2nd paragraph, and would accordingly feel no compunction about doing anything Allah commanded. Blowing up a marketplace or shooting a girl on a schoolbus might seem bad in a normal context, but if Allah, who defines Good and Evil has ordered you to do it, in this specific instance it is defined as Good.
To help us in such a situation, we do have the Church to help us discern whether what you are interpreting as a message from God is really that or not. Demons have been whispering things in the ears of man since Adam, so if it seems to be contrary to the Natural Law, it probably isn’t from God or any pious supernatural being because He isn’t fickle.
I hope this helps.