That veers dangerously close to the discussion about whether or not one must acknowledge Christ to be saved, which is a discussion I really don't care to get into now... But essentially, yes. An athiest who lives by the "golden rule" can be as "God loving" as any Christian, at least so far as their acts and attitudes are concerned. Remember the parable of the Good Samaritan? That was kind of the point of it.
As to sexual immorality/loving others... I'm not sure what your saying.
It isn't the sex part, specifically, that is the "loving others", its the arriving at the conclusion that its OK that is the "loving others" part. I thought I explained it in the simplest possible terms a few pages back. Sexual immorality exists, and, to me, its pretty easy to determine. "Would I want someone doing that to me if I were them?" If the answer is no, then it would be immoral for me to do so. Thats all there is to it.
And it works for anything. Not just to determine sexual morality, but for ANY moral question... ask yourself honestly, if you are considering an act that will effect other people, and you cannot honestly say that, were you in the other person's position, you would want it done to you, then don't do it, because its immoral.
Now, lest obtuse people who like to argue for the sake of arguing butt in here, yes, there are occasions, usually to do with "greatest good for greatest number", or self defence or defence of others, where things get a bit more complex. However, the basic paradigm holds. If you always use it as your guiding principle, just simple little "would I want it done to me if our roles were reversed?", and you can't go to far wrong.
