Well I'm no fan of Catholicism, it is misogynist and patriarchal, like other religions.
Nor am I a fan of science deniers, I find them misogynist and patriarchal too.
Biological fact. Sex is determined by external genitals. Males have testicles and a penis and internally a prostate. Females have a vulva, clitoris with hood, urinary outlet, labia vaginal opening and glands; and internal organs vagina, cervix, uterus, fallopian tubes, ovaries. Some humans are born with undetermined external genitalia, but these humans are rare.
On seeing sex they will be given a gender, boy or girl who will grow up to be woman or man, and this is done now 95% of the time pre birth. With a gendered name as well.
It is assumed that most girls will be princesses and like pink and that most boys will be princes and like blue.
Gender and biological sex (determined before birth), are clearly different.
There are biological determinants that cannot be ignored, for example puberty. Those wishing to change gender cannot ignore this if their wish to do so occurs before puberty.