Objective Morality is of no use if God has mysterious ways

 
Suppose God is the objective standard of goodness. He will command some things for a mysterious purpose or if you prefer - he sees the big picture which is why he can command shocking things. We can't prove he is right for our vision is limited. A two year old cannot understand why the big bad dentist hurts her mouth.
 
The Church says God can command terrible things for they are the only or the best way under difficult circumstances. But it says he will never command you to engage in vice such as avarice or lust for a good purpose.
 
In Catholicism, God never ever commands you to have sex outside marriage (lust) or to think you are above God (pride) but will let you take a life when there is sufficient reason - eg self-defence.
 
Reason says pride or any vice cannot matter more than human life. Whatever that God stuff is, it is not morality. If religion reads this it will retort that God's ways are right but a mystery that we cannot understand.
 
God could command some evils for they are unavoidable. For example, if the vast majority of marriages end in disaster that will not stop him commanding marriage even though it is largely asking for trouble. Who cares then if morals are objective or subjective? Even if we establish that the God idea implies that there is an objective standard of morality, the problem of knowing what he wants us to do makes us wonder why we bother trying to establish that. Maybe God needs us to think that morals are subjective for some purpose?
 
Even if goodness is God's character, we still need to judge if he is good and we can only do that by checking it out using a standard he has not set up. And that will be our own interpretation of a standard or the standard. People who adore God's standard are really talking about their own.
 
A truthful person can be forced to say what they know is not true. They are not called liars when there really is no choice. But if God has to let babies die horribly because there is no choice then how can you be sure that all he says is true? The God concept is no good for telling you what to value or do. Vengeance would be objectively good if it was unavoidable and necessary for some greater good.
 
God supposedly has written natural law into us. This is said to be why we sense and see that stealing is wrong. If God is able to put such a good match between what he says morality should be and what we would want it to be then the mysterious purpose stuff loses credibility. It is even insulting to him if he exists.
 
People try to unify God and moral rules by saying God is the ground of morality. But even if he is, they are not getting what they want. It is not enough to uphold their rules. Using it to uphold rules in fact is immoral!