Well first off, Christianity is not an ideology. There are certain elements of Christian teachings that deal with socio-political issues; the Protestants have the Social Gospel, and Catholics have Social Doctrine.
Homosexuality is a sin. Within the Catholic perspective, I believe the notion commonly is that homosexual acts are the sin but not necessarily homosexual inclinations per se. You just can't act on those inclinations.
If Homosexuality is indeed genetic(Im not debating the issue whether it is or not), that still doesn't change the fact that it's a sin. Of course this will put plenty of internal pressure upon people with such inclinations. We know it, and we understand.
The life of the true Christian is one of constant struggle with ones flaws and sinfulness, and of course laspes will occur. We understand, and we wish to show compassion when that happens. It should probably be noted that God does acknowledge honest efforts to stay on the right path, even when we ultimately fail in doing so.
Within Catholicism, we have the sacrament of reconciliation(confession), where we come before God and asked forgiveness for our wrong-doing. In doing so, we are forgiven and brought back in God's good graces.
God does not want us to hate ourselves, he wants us to love ourselves in proper form(geniune self-love is not the same as pride mind you). As even my own confessor once said, Satan is interested in undermining ones faith, and certainly one sneaky way he does it is by convincing you you're worthless before God. One must constantly resist such thoughts. Sin does not make you worthless before God.
As St. Padre Pio once said:
"God can reject everything in a creature conceived in sin and of which it bears the indelible impression inherited from Adam. But He can absolutely not reject the sincere desire to love Him."
The great irony I find is when people criticise Christianity for claiming that man is sinful, claiming that means man is worthless before God. That's not all so. If God thought so, he wouldn't have sent his son to die for our salvation. It should also be noted that the Bible claims that man was created in God's image. That happens before original sin.
And the incarnation of Christ also shows the close relationship between the human and the divine, as Nikolai Berdyaev explains:
"Christianity is not only belief in God; it is also belief in man, and in the possibility of a revealation of the divine in man. There exists a commensurability between God and man and on that account only is revealation of God to man possible. Pure abstract transcendentalism makes revealation impossible; it cannot open out pathways to God, and excludes the possibility of communion between man and God."
Martin Buber also further elaborated upon this, claiming that according to the Biblical tradition, the relationship between man and God is based upon the
I-Thou relationship. We connect with God on such an intimate level, which is not readily seen in many other traditions.
I think I've drifted from the original topic here. Applying to homosexuals, we can also address this from the basic Existential argument of
Existence preceding
Essence.
Long story short: Homosexuals are not somehow sub-human for being homosexuals. They're still people, and sinners like anybody else. In this case, they have their own particular demon to face; just like we have our own particular demons to face.
And I'm beginning to loose my train of thought, so I'll end it here.