We liberals are well aware of personal virtue. We tend to see conservatives as seeing sin only in terms of personal action, especially sexual acts -- what you call "true sin". Conservatives tend to ignore social sins, even though the biblical prophets don't talk about personal sins that much, they rather say things such as 

Is not this the fast that I choose:
to loose the bonds of injustice,
to undo the thongs of the yoke,
to let the oppressed go free,
and to break every yoke?
Is it not to share your bread with the hungry,
and bring the homeless poor into your house;
when you see the naked, to cover them,
and not to hide yourself from your own kin?
Then your light shall break forth like the dawn -- Isaiah 58:6-8

Jesus, in Matthew 25, tells us that feeding the hungry, clothing the naked and so forth are what are necessary for salvation. He says nothing about not living in same-sex relationships. 

The sin of avarice is, to my mind, far more important than lust.