This is based on the translation of an obscure Greek word arsenokoites. It is claimed time and again by those seeking to justify personal prejudice that the word obviously means homosexual, but there is no evidence to support this assumption.
For most of the history of Christianity arsenokoites was translated to mean masturbation, the most recent bible to make this translation was 1968. It is only in the last fifty years or so that a shift in the translation of this word to mean homosexual has been seen.
The defense for claiming that arsenokoites means homosexual is made by claiming that the meaning of this compound word is derived from the meaning of its two root words: arseno (man or men) and koitai (bed). This approach is linguistically invalid. Deconstructing compounds is difficult no matter what language one uses. One cant just define a compound word by taking it apart, getting the meanings of its component parts, and then assuming, with no supporting evidence, that the meaning of the longer word is a simple combination of its component parts. To "understand" does not mean to "stand under." In fact, nothing about the meaning of understand has anything to do with standing or being under anything. This phenomenon of language is sometimes even more obvious with terms that designate social roles, since the nature of the roles themselves often changes over time and becomes separated from any original reference. None of us, for example, takes the word "chairman" to mean a man who sits in a chair. Therefore all definitions of arsenokoites that derive its meaning from its components are indefensible. Using this method it would be equally valid to claim that when using the word arsenokoites Paul was condemning the lazy or even the bed making industry.
I wondered when someone would bring this up. The claim is a joke among linguists and etylogists. Some claim that Paul coined this word by combining two words from the Septuagint because his audience would have no reference or understanding of homosexuality. The ancient Greeks clearly understood the concept and didnt have to make up words to discuss it.
The real trouble occurs when one looks at the what actually appears in the Septuagint.the phrase in the Septuagint "kai meta arsenos ou koimêthêsê koitên gynaikos bdelygma gar estin" is saying nothing about homosexuality or even male to male sex. rather it is condemning adultery, specifically adultery where one of the participants is a sanctified man and then only during the time he is sanctified. Notice there is no prohibition of the sanctified man having intercourse with his wife or wives or even his concubines, rather it is about bringing another woman into the marriage bed during the time he is sanctified, a woman his is not and cannot be married to. And even then that condemnation is limited to changing his status to one of ritual impurity, not sin or even the lesser no-no abomination.
If you're going to use this justification to pretend that arsenokoites means homosexual when used in 1 Corinthians 6:9 then you pretty much have to ignore all dozens of other times arsen and koite appeared in Leviticus when referring to obvious heterosexual sexual acts