Articles related to Book Topic

I'm working on a book proposal and book. That has me thinking about my "credentials." In order to build my writing resume, I'm thinking of trying to get some non-fiction articles published. I would like to write articles around the same topic as my book because that would show my knowledge on this topic (and because that is where my mind is right now).

My concern/question is the boundary line regarding how similar/different the material needs to be. I understand that I can't have an article published and then hope to put that same writing in my book. No problem. That is reasonable. But can it be about the same idea/concept?

My book is about spiritual issues related to childhood abuse. So if I write an article about, say how the Parable of the Prodigal Son helped in my healing. Can I still use the same idea if I write it again fresh, and expound on it more in the book?

Thank you! That is very helpful...and what I hoped the answer would be.

Good point Gatita. I need something in the credibility department too! I know I can do this, but convincing an agent or editor is another matter.

Thanks Kudra, that advice resonates with me and answered an unspoken question about the direction I should go with my blog. i have been blogging for a few years on a related topic. So lately I have wondered if I should change the blog direction a bit to follow the leanings of the book...I think some of my readers would like it, but others I am not so sure about. Reading your post helped me make a decision. I'm going to keep things as they are. Thanks!