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On the other hand, the Orthodox belief is that Mary reached a state of theosis that can and never will be attained by anyone else
First, and as an aside to any Protestnat reading this, these are the superabundant merits of Christ that she dispenses, -- none of her own, as she remains fully human, -- in fact, more human than we are. There may be a difference indeed because as I understand the Orthodox Church teaches that the grace flows equally to all, whichis not the Catholic teaching in general (see the Parable of the Talents why).
The second part of your post shows that despite the great differences in theological method, we arrive in the same place insofar as our needs in praxis are concerned. Surely you don't think it ill-advised to ask for Mary's prayers, especially when in the hour of our death our own pious disposition might be not at its height.
You are never ever told to pray to Mary. She is singled out by Jesus Christ as being the same as any believer, nothing more, nothing less.
If you are praying to Mary at your death, you can best believe that the next thing you see will be Satan in Hell.
Mary does not save, she does not offer salvation and she can not hear you nor help you.
1 Timothy 2:4 Who will have all men to be saved, and to come unto the knowledge of the truth.
5 For there is one God, and one mediator between God and men, the man Christ Jesus;
6 Who gave himself a ransom for all, to be testified in due time.