to book an appointment for tomorrow. She has her own website and more than 20 excellent reviews on TER. I gave the usual info then pressed send. Two minutes later I received a really bizarre reply. It was just one rambling sentence that made no sense, didn't pertain to the topic, wasn't grammatical, but used some religious language. I didn't reply thinking maybe this was a sign to not see this provider. You can't make this stuff up, any thoughts?

Maybe you dialed wrong, or maybe you dialed correctly but her phone number was incorrect on the ad or profile (wherever you got it.)
Maybe it's an old phone number and someone else has that number now.
Maybe she lost her phone and someone else is replying.
Maybe a boyfriend, or SO found her phone, or some family member or friend. Maybe they are really pissed, or maybe they're playing a practical joke on her.
Maybe she is drunk, high, or Just BSC.

Yeah, I know. Nobody is surprised.  

I've had it happen that I thought I was replying to one person via text and someone had texted in between and mistakenly texted the second person.  

I only text for small details like the name of her hotel.

...of problems like the one OP encountered, for one example.

In general, there's a practical limit on how much information you can offer about yourself in a text message.  I can't imagine a provider feeling comfortable about making a date with a brand new client from a simple text exchange. I always email, provide references, prove that I'm at least semi-literate, etc.

Texting for a first date feels like a booty call to me.  Not very respectful of the lady.

But hey, that's just me.  Maybe I'm a bit old-fashioned.

or one of our 10 year nursing students. Is the provider from Boston? Regardless, find a lucid hooker and skip that one.

.... so many here would go dateless.

Even if I already know the girl, and know the number is correct, I always start (a new conversation, a different day...or whatever) with a simple "Hi" and wait for a reply.  Otherwise you don't know who may have the phone.  

How about just being honest and straight forward and text her back that you did not understand her reply. Reiterate your question. Then, if you get a garbled reply again, you know that something is amiss.

It depends on the lady's preferred method. Sure I usually use email (or PM through a site like this or P411) but I have also used texting to set up first dates.

Some providers are not too grammatical because they are foreigners so English is their second language.  
They usually learn more English in college in US but it takes them long time  to perfect their English grammar.  
I was born in eastern Europe so it took me 4 yeas to graduate college.  
I had to read more then 5 English books, do lots of English tutoring.  
My grammar improved over the years but you probably say that my grammar is still bad.