I suspect your word order may cause confusion here, Spud, since I doubt there are few places where people who are 'at work' are asked to support the practice of any form of sexuality, aside obviously from those involved in the sex industry.
If you mean that while in the course of your job that you should be able to decline to deliver or sell newspapers and magazines you personally disapprove of then you are clearly in the wrong job: tell me Spud, would you decline to sell me my usual Saturday copy of The Racing Post?
Ashers bakery is an example. Or the B&B owners who are asked to provide a double room, the dating website asked to extend its service to same-sex-attracted people. I suspect most Christians in business could face this dilemma in some way.
Re: the Racing Post. To be honest I haven't thought about it - a friend of mine who bets on horses says the money is well spent as it keeps the horses fit (interesting logic). I do occasionally take money for a Racing Post at the till, but I have said that I won't do till work for this shop regularly because of the amount of cigarettes, alcohol, lottery and porn that is available. So I stick to paper delivery. I would recommend you don't bet large amounts or regularly.
The agreement was to deliver national newspapers and other magazines such as Radio Times; I had one that I think was called "Woman". If there was more of the trashy stuff I would definitely move on. I never thought I'd be asked to deliver something like the one in question.
I'm not sure what you mean by 'supporting the practice of homosexuality at work', unless you mean 'not discriminating against gay people'. But you don't seem to be aware that many Christians, if not most, don't care if someone is gay, don't care if they have a partner and view marriage equality as a chance to go to more parties. It's only a minority who can't accept it. But yes, if you can't not discriminate then you shouldn't be in a job that deals with customers or clients.
I would happily deliver a newspaper to a gay person. But if a gay magazine's primary purpose is advising the reader about sexual relationships with someone of the same sex, then I would be condoning that by delivering it.
All paid work involves dealing with customers or clients. What you have suggested amounts to, don't work for money. How does one pay for food or clothes, then? What about the useful aspects of the job such as helping the elderly lady who can't get to the paper shop?
No, I think Ashers bakery were within their rights to refuse this business. They took the decision not to take the customer's money. You, on the other hand, took the decision to accept your employer's money, so you should do the job you were contracted to.
I agree about Ashers.
When I accepted the job I was not told I might be asked to deliver gay magazines. When I was asked to deliver them I said no - they were then free to sack me; they decided to keep me on.