A valid question. Outside Christ, all sin separates one from Holy God. However, God is also just and fair so it's no surprise that the Bible teaches sin gradients. The Mosaic Law itself which formed the core of the old covenant God had with the ancient nation of Israel is a perfect example; however, the New Testament itself is replete with them including Jesus Himself telling Pilate in John 19:11 "therefore he that delivered me to you has the greater sin."
So all sin separates one from Holy God outside of Christ but justice acknowledges that sin gradients. Sins like murder, for example, are actually worse than say taking a pencil from work without asking. Keep this in mind moving forward as we look at God's design for humanity.
Look at Genesis 5:2, "He [God] created them male (1) and female (2), and He blessed them and named them Man (3) in the day when they were created."
1 male = זָכָר
2 female = נְקֵבָה
3 Man = אָדָם
In ancient Hebrew, these words have very specific meanings. 1 male means a biological male not just a gender role. 2 female means a biological female not just a gender role. 3 means mankind or humanity encompassing both biological males and females with the gender roles that each were designed for.
Now God created males and females biologically distinct and it's together they receive His mandate and blessing to be fruitful and multiply and have dominion over creation (Gen 1:27–28). Together a biological male and biological woman are complete (Gen 2:18–25). The very pairing of man and woman in the assertion "male and female he created them" (Gen 1:27 RSV) implies that together the two biologically different sexes make up humanity and the great manifestation of this essential unity is marriage (Gen 2:23–24) between a man and a woman.
So in the Genesis 1 creation account, Adam emerges as "the human" (hā’āḏām, Gen 1:26–27), differentiated as a biological male and biological female (e.g. "male זָכָר and female נְקֵבָה He [God] created them.")
When Genesis 1-3 is lined up next to Ephesians 5 we see that husband and wife means a biologically differentiated man and woman and that this was God's intent from the beginning.
Homosexuality is sin like all other but it gradients differently than say fornication (which is also serious sexual immorality as you rightly state) because it's a choice to exchange God's design for unnatural purpose. As an "identity," it's rebellion against a holy Creator God and His design for humanity.
In fact, homosexuality as an "identity" is a recent non-biblical ungodly construct that modernists and post-modernists began to assert around the sexual immorality of homosexuality.
While references to homosexual acts are limited in Scripture, they become a powerful image for those who in their rebellion and blindness choose to give up God’s good gift of normative morality in healthy sexuality and exchange it for something degrading and unnatural.
Homosexual acts become a symbol in Scripture for violating a basic principle of holiness: mixing that which the Lord declared should be separate.
In Romans 1, Paul condemns homosexual acts, lesbian as well as male, in the same breath as idolatry (vv. 23–27), but his theological canvas is broader than that. Instead of treating homosexual behavior as an expression of idolatrous worship, he traces both to the bad ‘exchange’ fallen man has made in departing from his Creator’s intention. Seen from this angle, every homosexual act is unnatural, because it flies in the face of God’s creation scheme for human sexual expression.
This accounts for the strong language in the Bible that those who choose to unrepentantly engage in homosexual acts can eventually become reprobate at which point God lets go giving them up to their lusts (Rom 1:18–25).
It is one thing to repent and become a Christian in recovery/sanctification struggling with sin issues, relying on God's grace, while steadfastly seeking repair from Creator God towards sanctification. This is the condition many Christians find themselves in. Perhaps all of us, to some extent myself included. We are born-again and have aligned ourselves with our Creator and His truth and earnestly desire and commit to be whole moral people.
It is entirely another to engage in willful rebellion against the one true Holy Creator God and forsake His morality, forsake His natural design for humanity and good plan for one's life, adopt a sexually immoral identity to live out as a "lifestyle," and then either repudiate His Word entirely or malign it to "justify" all of the above.
And while one can certainly act in a similar way with respect to other sexual sin, this is why homosexuality is a greater sin than fornication and why the Bible speaks so strongly against it. This fantasy being propagated at present in our culture that homosexuality is equitable with heterosexuality and that homosexual marriage is equitable with heterosexual marriage is a great deception for this reason.
There isn't a homosexual marriage on the planet that ever will have God's recognition as legitimate and blessing. In spiritual terms, the act is a sacrilege of marriage.
Remind me at a later date to show you the studies from Oxford, Harvard, etc... that 20th century anthropologists published showing what happens to human civilizations throughout history that discard absolute monogamy as is occurring now in Western Civilization. Yes, scholarly historical and anthropological studies exist on the topic and they are quite enlightening. It appears entire civilizations can reach a point where God withdraws His hand of blessing when they forsake His design and good purpose for them.
I am against gay marriage and also people having sex before marriage and people doing drugs, but how is it that Christians pick homosexuals as horrible, but not flag the other two to the extreme??? To me its all the same, its all a sinful lifestyle that is against God, none worse than the other. It may affect differently, but still sin.
