The pure definition of discrimination is never evil of itself--if you wish to hire a worker, you discriminate according to which worker will give you the most benefit. When you marry, (disregarding issues of commands from God), you should choose the person that will make the best spouse for you--this readily rules out fornicators and adulterers. When you have coffee with someone, is there a line of people you are going to reject, and who you are going to accept? Is there rejection?
The question of discrimination in the workplace according to personal morality is simple--it's just not any of your business. It is improper for you to ask a person if he's a homosexual, or an adulterer, in a job interview. That's not why he's there, although asking him if he's committed a felony IS quite relevant. What a person does behind the walls of his home is irrelevant--what matters is how well he can perform the task you are going to pay him for. On the other hand, however, while I could care less about a person's sexual orientation in the workplace, if I'm a retail manager, I wouldn't think twice about throwing an application in the garbage if a male applicant showed up dressed as a woman. While the same standard doesn't apply for acceptance as a friend, or for all occupations, it is quite obvious that an individual who is in such a denial of himself would not be considerable for a position in that particular field. Of course, we cannot rule out those particular *christian* individuals who think that Christ's "tell the good news to all people" means that they are supposed to neglect the duties of their job to hand out leaflets. So, the bottom line is, as an employer your only concern should be those things that are relevant to your facilities, and nothing more.
Is it good to discriminate according to morality when one is looking for a spouse? OF COURSE IT IS! It is insane to say that it is not! Is it good to discriminate according to religion, when looking for a spouse? OF COURSE IT IS! The Bible itself says that we should do so. What about other things? Sure. There are some things that people do that are not wrong, but they do have an impact on whether or not the person in question would make a good spouse for one specific person. Furthermore, now leaving wisdom and speaking purely on morals, a person's hand in marriage is his to give. Unless there is a command from God, discriminating for any reason is not unjust when we are speaking about marriage. If I don't want to marry a lady because she has a funny laugh, that's my business. I have done her ABSOLUTELY NO moral wrong by refusing to date or marry her. (Of course, if I dated her for 10 years and was engaged to her, then suddenly decided to break it off because I didn't like her laugh, THEN there might be a moral issue.)
Now, concerning friends...ugh. I'll talk about friends later. Friends are different--Christ gave us an example to follow. Much of what I'd say about it has been said already, so I'll put my 2 cents in about friends next time. Blessings.