I am considering a job transfer to Jeddah. I'm a devout Catholic. I understand that I'll be moving to Muslim country and cannot openly practice my faith. Is it possible to watch daily mass via YouTube or read my bible via internet or do they have these sites restricted? How do ex pats practice their faith in hiding without coming foul of religious police?
Unfortunately there are no Christian churches in Saudi Arabia and it's against the law for Catholics to practise their religion openly. Though the internet is heavily censored in Saudi Arabia, most of the barred content is either pornographic in nature or is related to anti-Islamic activism, so there is a chance you'll be able to access religious content. Physical objects related to any religion other than Islam are banned although in practice, sometimes such artefacts are kept privately in the home.
Proselytising is strictly forbidden and carries the death penalty, so it is extremely important to keep a low profile when performing any kind of non-Islamic religious activities.
You can read more about religion in the country on our page Culture Shock in Saudi Arabia.
We also have an article about Religion and Worship in Saudi Arabia, but bear in mind that some content might be slightly outdated as this particular article was written a few years ago. It's still worth a look, though, as it discusses the issue in depth.
Best of luck.