The use of the term Gender has its origin in grammatical use for feminine and masculine words. However, in the 1950s vile, pedophilia advocate John Money joined John Hopkins and invented out of thin air the separation of Gender of Male or Female from being determined by sex. He did this by changing the definition of gender from the masculine and feminine forms of grammar such as he or she which had always corresponded to ones sex being addressed. He made it mean, "social expression of an internal sexed identity."
Other words the term as an Identity existing outside your biological sex in medicine and psychiatry comes from someone whom had an agenda. A transsexuality obsessed, propedophile legalizing vile monster. Whom wished to redefine Gender as the grammatical to meaning the expression of something other than just expressing maleness or femaleness with your own personality.
If that is the case gender expression, gender identity and gender conformity are all terms linked to the second form of the term Gender. Which means they are playing into the idea that there is an internal identity apart from your own Male of Female sex.
We know scientifically that there are thousands of genetic differences between males and females. Your chromosomes for example will determine if your body will have more of a possiblity of rejecting Kidney replacements. Every inch of your DNA is saturated with differences depending on your sex chromosomes. We do not assign a sex we acknowledge it based on your DNA.
What is often called gender nonconforming or expression in general is all based on the idea that a man or woman with certain traits are somehow expressing a different internal gender or internal sexed trait from their biology. Which is impossible scientifically and based more often then not on stereotypes of what a man or woman is.
There is an even more important layer as well to people affirming and accepting gender expression/conforming language. That being the integrity of The Word of God. God speaks in his word in the Creation Account of creating the two sexes Male and Female or man and woman. It never once says it created the Gender Identity or Expression of --the fill in the era---- typical man or woman.
All male/man can be is man as created by God and female/woman as God created her. What is called gender expressing or conformity can never truly be conforming to anything other than the man or woman that you are. Thus you are not expressing a Gender Identity, but, instead your sex as Created by God in your own way.
All men at a DNA level are masculinized and all women are feminized. You have a penis and testicals which comes from masculinization by God via the Womb and your DNA. Or you have a vulva and are feminized in the Womb and via DNA. By expressing yourself within the body and with the Chromosomal make up you have equals always confirming to your sex.
Thus gender nonconforming is an unscientific useless and nefarious evil term designed to separate your personality into being "Gender atypical or typical." To separate ones individual personality or interests from being a form of normal expression within Gods providence for you as the man/woman/boy/girl you were created to be by his Soveriegn Almighty Hands.