This is a fundamental misunderstanding of the Christian position on homosexuality, which the media purposefully spread by focusing on the Westborough Baptists and their insanity.
Firstly, "being homosexual" is not a thing as far as Christian morality is concerned. What matters in Christianity is thought and actions, and homosexual acts and lusts are defined as sinful. Note though that heterosexual acts and lusts outside of marriage ARE ALSO defined as sinful, to be non-sinful sex and related activities must take place within a marriage.
Note, "lusts" is not the same as "attraction", one can recognize beauty or physical attraction without succumbing to the sin of lust. It's the difference between seeing someone that is attractive and acknowledging that you find them attractive, and ACTIVELY FANTASIZING about them. The first is perfectly fine, the second is what falls into the category of lust and is thus sinful. This applies to both heterosexual and homosexual attraction.
As far as "being homosexual" is sinful it is in the constant indulging in and refusing to refrain from the related sins that make it bad. It more properly understood to, say, having a temper and refusing to control it or restrain it and even being PROUD of your temper.
Someone who is attracted to the same sex, but doesn't actively lust over people or engage in sexual or related acts... hasn't actually sinned in that way. From a Christian perspective they have an area of specific temptation they struggle with.
Finally, here's the big thing that people forget about Christianity: Christian believe everyone is Evil. Everyone is Fallen. The homosexual is Evil and Fallen, but that's not because they are homosexual, but because they are HUMAN. EVERYONE is Evil and Fallen short of God's standard, which is why there is a need for sacrificial atonement by Christ to make up for EVERYONE'S failings, and everyone needs to work to overcome the various impulses that lead them to sin, some just have different areas of temptation than others.