...How would YOU feel if you made something beautiful and then someone came along and altered it?...
Adam and Eve already did that. Eve and Adam disobeyed God and brought the curse of sin into the world. Now we witness the result of thousands of years of genetic degradation and mutations when children are born with both mental and physical handicaps. When possible we try to "fix" these defects so a person can have a more "normal" life.
In the beginning God created them male and female, but in the present day, humans are sometimes born with both male and female genitals, some ambiguous, and some without genitals. Some have "male" XY chromosomes yet are in appearances female, even having a uterus. Others have DNA with "female" XX chromosomes yet are anatomically male. More than one in 500 males have an extra X chromosome. There are many natural variations that do not conform to typical male/female sex characteristics.
Research is increasingly finding evidence that links genetics and prenatal hormonal conditions to gender dysphoria. As a birth defect (and therefore not a choice), why shouldn't that defect be corrected so a person can have a more normal life? Can we judge with certainty that gender dysphoria is simply a sinful choice rather than a birth defect?
Further, with regard to transsexuals, why do many Christians place so much emphasis on the flesh or physical characteristics while completely disregarding the heart of the individual? I find this to be curious when considering the following...
1 Samuel 16:7 (NKJV)
"...For the Lord does not see as man sees; for man looks at the outward appearance, but the Lord looks at the heart.”
John 7:24 (NKJV)
"Do not judge according to appearance, but judge with righteous judgment."
...if they are having sex with 1.) someone they are not married to, they are going to hell for the Scripture tells us that fornicators do not access the Kingdom of Heaven; or 2.) if they are married to someone of the same sex as they were when they were born, they are going to hell because they cannot be Biblically married to a member of the same. sex...
Let me address this in reverse order...
2. One born anatomically male with severe gender dysphoria cannot have a truly heterosexual relationship with a woman; in their heart and mind this would be a homosexual relationship. If this person undergoes sex reassignment surgery, she will be female anatomically as well as being female in heart and mind, and I see no reason why she couldn't marry a man. It would be a heterosexual relationship in both ways.
1. Jesus taught clearly about divorce being sin, yet divorce is very common within Christianity, even with church programs to help divorcees reintegrate into the church. I have even met several pastors who are divorced. Applying your logic, about 2/3 of the "church" is going directly to eternity in hell as a result of divorce/remarriage. Scripture does not have the same clear prohibition of someone with gender dysphoria undergoing sex reassignment surgery. Why does the church tolerate divorce while condemning transsexuals?