I hope you all have a lovely day,Butternut - the weather is gorgeous here in Haute Savoie!
I did teach in two Catholic secondary schools in the 1970's. They knew I was a 'recovering catholic' - i.e. an atheist who had been brought up as a catholic. I was actually allowed to draw up the syllabus for EPR (Education for Personal Relationships!) and to cover the various forms of contraception. The syllabus was approved by the Chairman of the Governors, who was a priest.I just had to say at the end of each lesson ' Of course, your church does not approve of most forms of contraception, other than the rhythm method'. Many mothers came up to me on Parents' nights and thanked me for the information which they themselves really needed.
I was asked to attend assembly and services to oversee my 'lively' remedial pupils, but was not expected to join in with any of the prayers or hymns. (Actually, I quite enjoy singing hymns, but there was a principle at stake).
I had no qualms about working in catholic schools as I felt I was able to soften the hard regime and my attitude towards corporal punishment (totally opposed) certainly helped to change the headmaster's attitude.
If the pupils asked me why I did not join in with worship, I told them the truth - that I did not share their religious faith. This was in the days before schools taught about the major world religions - they were told simply that Catholics were right and everybody else in the world was wrong. I was able to give them some information about other faiths and other 'stances for living'. No parent ever complained.