-Removed-I have to agree with the first part of your statement. I am not read up on Ken Ham however so I don't really feel qualified to make a judgement.
This reminds me of books about the end of the world which come out every now and again. If the world is ending why sell a book, better to find a way to give it away thus impacting more people about the end then making a profit.
-Removed-That's a completely different topic. I already stated that I don't think religious organizations should get tax breaks. There's no reason for it. But as for if they should be allowed to profit: why not?
Getting back to the OP, they should be allowed to hire all Christians, given the evangelical nature of their business. Since they may want their employees to share their faith with the public, or maybe even pray with them, the only way they can do this without trampling on their employees rights is by employing only Christians.
If this was a Christian-owned cake shop with the goal of selling cake, then it would be different. This is a religious organization with religious motives opening a religious theme park. If they make millions from this theme park, it still wouldn't change this fact.
I have read a few articles on this theme park, and what struck me was that ALL denominations of 'Christianity' are welcomed to be employees.....doesn't seem to matter whether you are Protestant, Baptist, Catholic, etc. The article did not mention Jehovah Witness which is curious.
Just using this forum as an example, it seems to me that if you lump hundreds of Christians together in a theme park.....and they have differing views, interpretations, and opinions of Bible text, that you could be asking for some intense 'debates' in the lunchroom cafeteria.....or in front of customers. Just requiring employees to be a 'Christian' doesn't seem to avoid the possibility of conflict.....the same as if an atheist worked there.
Just my opinion.