Bottom Line
Sexuality is a plumbing issue. Gender is an emotional identification.
A more sophisticated description
Sexuality refers to God’s anthropological design and pattern for the procreative relationship between male and female and to the experience of erotic desire within that design. Gender refers to biological differences in male and female embodiment and the different cultural ways in which the creational distinctions between male and female are manifested.
Right answer
The Bible outlines in Genesis 1 and 2 that God created two sexual/genders: male and female. Never in the rest of recorded Scripture did God alter this or add anything to human creation. Therefore, there are only two sexual/genders: male and female.
Human answer
Here’s the challenge. When Adam and Eve sinned in the garden, sin entered the world. Along with sin came a distorted reality of all that God had made. Everything slowly became corrupt, included sexuality. We are all born into some type of sexual brokenness and need Jesus to wash away our sin. Then, we need to walk toward healing by following God’s Word. For some, sexual brokenness comes in the form of lust. For some, it is the desire to have more than one sexual partner. For others, it is wanting to have sexual encounters with people of the same sex. Still others, it is the feeling of identifying as the opposite gender. This is just as real and just as hard to deal with as the guy who is struggling with porn. You cannot just “turn it off” or pray it away. You need prayer AND healing. You need the long, slow walk of freedom that comes from doing life with God and with God’s community.
This is why heathy sexual teaching from God’s Word is so important. God doesn’t hate people who struggle with gender confusion. He loves them just the way they are… but He also loves them too much to let them stay that way. He wants them healed, whole, and back to their original design. That is to be holy in their sexuality.
What breaks my heart the most is there are too many who think that loving others is not being honest about the warnings in God's Word. God's Word was written for our benefit. God gets no glory out of telling us to stay away from things. It is for our freedom. So, when God's Word declares there are only two genders, we are hurting people by telling them anything else.
The only other thing to say is Christians bring shame to the Name of Christ when we use God's Word to bash people over the head. If you are not prepared to walk with someone, you're not fit to preach to anyone.