The way I see it with respect to trans is this: God puts the soul into the body and Satan can do nothing to your soul without your consent. However, Satan can easily muck about with physical matter, including our bodies. If there is a discrepancy between the gender of the body and the gender of the soul we can say one thing; God doesn't make mistakes, so it must be the body that is out of order. By allowing a trans person to transition and be accepted within the community, we set things back into harmony with God's plan. By that argument, being anti-Trans can be considered a sin.
This can also be seen in many intersex people who have a particular gender identity but who may have ambiguous genetic characteristics. This could be argued to be proof of Satan mucking about with the person's genes to trick him/her into a path of sin.
If you are of the Christian systems that don't regard Satan as an actual entity, but as more of a metaphor, you can just point to our physical bodies as being imperfect forms made of crude matter that don't always correspond to our perfectly-born souls.
Of course, plenty of religious authorities would argue that I am just repeating lies whispered to me by the Ol' Deceiver. Funny thing about the Bible; you can use it to prove just about anything and someone else can use it to disprove everything you propose. Ultimately, you just have to go with whatever your heart says is the Godly answer.
