I've got a question and a challenge for the Christians who very strongly believe that being transgender is sinful...
It's easy to get online and say how evil transpeople are, but have you ever prayed for a transgender person... by name? There are a few to choose from here on this thread.
I challenge you to do this - pray sincerely and often for a transperson - not for God's wrath, nor for them to recognize how vile they are (as many transpeople likely would expect), but pray for those that believe in God to be faithful, and for those who do not, that perhaps they would experience Gods great love, mercy, and grace, and that they will come to know and believe in Him.
I think (and believe) that praying for transpeople will have a profound effect on your perspective, to help you recognize that we are all humans in need of salvation, because all have sinned and none of us are righteous on our own. It doesn't really matter what the sin is; all sin is an abomination. Yet God made a way for all of us vile sinners to be forgiven, and made righteous by confessing our sin and by believing in Jesus our Messiah we will be saved. The Christian must not lose sight of this reality and think more highly of themselves than they ought.
I pray that all of you who believe will seek to be a conduit for Gods great love, mercy, and grace.