Is sexual orientation a concept that Christians ought to use?
No. Biblical personhood (what philosophers call ontology) is found in Genesis 1:27. It reveals that all who are redeemed by the atoning blood of Christ are male and female image-bearers of a holy God with a soul that will last forever and a body that will be glorified and redeemed in the New Jerusalem.
Sexual orientation as a category of personhood began as a 19th century category mistake, fueled by Sigmund Freud and German Romanticism. Freud was seeking to find the answer to the question: What separates humans from other mammals? Because he rejected the biblical definition of humanity, his studies in human sexuality led him to believe that humans are different from other mammals because sexual desires exceed procreation. Freud introduced terminology that had direct bearing on people who are same-sex attracted. His studies moved homosexuality from a verb (what people do) to a noun (who people are).
This new category of personhood—seeing people as essentially sexual beings whose objects of desire designate separate species of humans (as Foucault says)—took hold. It quickly became a 20th century idol, fueled by the sexual revolution and the belief that sexual autonomy is an immutable right. And with the 2015 US Supreme Court decision in Obergefell v. Hodges, sexual orientation as a category of personhood became a civil right, appended to the 14th amendment. The belief that sexual orientation is a category of personhood is on a collision course with the gospel.
By no means is my rejection of the category of sexual orientation a rejection of people who are struggling with same-sex sexual desire or a rejection that that desire is both real and unchosen. I am saying that sexual orientation as a designation of personhood (who you are) is a category mistake—a mistaken way of talking about people. There is a world(view) of difference between saying that you struggle with same-sex sexual attraction and that you are gay. One allows you to stand apart from your struggle, seeing homosexuality as a part of the Fall; the other collapses your identity into your struggle, seeing sexual orientation as a morally neutral reality.
Understanding sexual orientation as a category mistake is a little like understanding that Pluto is no longer a planet. No one disputes that Pluto as a planetary mass is real; the debate is whether its category as a planet is accurate.