One uses the indicative for facts, and the subjunctive for uncertainties.
One uses ‘estar’ to indicate temporary condition, and ‘ser’ to indicate permanent state.
Soy alta. = I’m tall.
Estoy contenta. = I’m happy/content.
The reason ‘ser’ should be used in this case is that whether or not it is a miracle does not change. It either is, or it isn’t.
Indicative versus subjunctive is a whole different can of worms. You can use ser and estar in either mood (indicative or subjunctive) it just depends on the context and the idea that you’re trying to get across.
Puede usar ‘estar’ en el subjuntivo. Por ejemplo, “Monica est’e loca” = “Monica might be crazy.”
‘Where is the dressing table?’ Am I understanding you correctly?