A sad example of man's inhumanity to man. Whether related by marriage or by blood, you have a right to expect to be treated civilly and shown respect. That right exists as long as you do nothing to invalidate it.
Those that state reptiles are evil, let alone if they believe it, are absolutely living in the dark ages. In fact, I would suggest that they would need to yawn very widely indeed just to see the light of day.
Prophecies of religious damnation because one has an affinity for snakes really are over the top. The serpent copped a bad wrap in the Garden of Eden and we are still hearing about it!! No-one mentions apples or the part they played.
If only these self-proclaimed religious knowledgeables took a longer, harder look at the bible, they would clearly see the recurrent message is to love your fellow man. And that is love in the true sense of the word – what you DO for others.
Where individuals in a position of influence are spiteful to your children, that is one of the lowest of the low. You would be well justified in choosing your best string of explicatives and letting them have it with both barrels. Unfortunately, any lack of civility is guaranteed to be used against you to strengthen the argument you are headed the wrong way. Therefore, your only recourse is rational argument.
The devil took the form of a serpent, yet all snakes are 'evil'? Does it include Blind Snakes? Do you know how many thousands of different snakes there are? Do you know that lots of them do not have fangs and therefore do not inject venom? Had he taken the form of a dove, would we feel the same animosity to all doves? If God is responsible for creating all creatures, how come he made one group "evil"? Are sharks evil? Bears? Lions and tigers? Do you know that snakes help keep mice and rat numbers in check and without them we would get lots more rodent plaques?...etc Ask the right questions and her ignorance (perhaps arrogance... or both) will shine through for your child to see.
Plan B is easier and based on the simple premise: If she gives you the sheets, you are entitled to do likewise to her. A teaspoon of Epsom Salts in her coffee should do the trick...
Blue