I am finishing my first book, as yet to be published. (Looking for an agent.) As I started on this book right out of the gate, I have no credits for magazine articles, etc. I am in the process of writing some devotionals and I was wondering if I can use two or three sentences from my book in the devotionals, or should I rewrite them? If I used them as is, how would this affect the rights for the book?
You can use your own work in devotionals. You own the copyright, and you can "give permission". If you get all nasty and cantankerous with yourself about permission fees, email me and I'll negotiate with your obstreperous self for a good deal from your nice self.
It doesn't affect the status of your rights in terms of a book sale at all.
If you published a big chunk of your book it might but most book publishers don't care much about that. (Magazine publishers and ebook publishers are a different story).