Look. It is indisputable that primary trans persons exist. I know a number of them (for some reason I seem to have a gravity field about me that primary trans folks wind up in my orbit for some reason...)
I spoke with my pastor, as a Roman Catholic (and I'd like to think a relatively strong one now that I've returned to the church) the church teaches that all people are, to greater or lesser extent, disordered. We are all sinners, we have all failed to fully live up to the ordered life of the ideal Christian. Even the saints have failed at some point or another, for they too were human. The only human to have ever been completely without disorder was Mary.
And he pointed something out. As the church simply calls trans individuals to prayerfully follow the call to live virtuous lives, rather than ipso facto condemns them as inherently greater sinners than any of the rest of us, that a MTF trans who fully transitions is called to precisely the same standard of holiness as a female born as such from the womb. The church, by the catechism, regards the trans issue in precisely the same way that they'd view any correctable medical issue. The church does not condemn somebody who requires surgery to correct any other condition for having said condition, so why would the church make an exception in this case?
I will note that this was specifically in regards to primary trans, and I agree with Tyanna that the loss of distinction between primary trans and secondary has been a great disservice to those who truly benefit from transitioning.
I will also note that there are many Catholics who take a hard line on the issue and conflate fundamental disorder with irreconcilable sin, but those are actually discrete doctrines. There are Catholics who misread the Church's teachings on homosexuality (no, the Church does not damn homosexuals, the Church instead calls homosexuals to remember the virtue of chastity, and that it is a violation of chastity to engage in sexual relations outside the sacramental relationship of marriage between a man and a woman. A practicing homosexual is no greater a sinner than a heterosexual philanderer or adulturur)
And for those who would bring up 'well transwomen in general cannot have children, so they can't be married', while infertility or impotence is a recognized factor for annulment of a marriage, it is not a blanket one. It is perfectly in line with doctrine and practice for, say, a widow and a widower, both well past the age of being able to beget children, to marry within the church.
It's fun sometimes talking about these sorts of things with a priest who happens to also be a trained canon lawyer *grins*