The university I attended for my undergraduate degree was actually a part of Colonial Williamsburg. We were seeped in history and most of us loved it, no matter our major. Our library was full of rare documents from people like Thomas Jefferson and other historical figures. As a result, one of the principles we were taught was the idea of researching primary source documents.
A primary source document is considered to be the closest source you can find to an actual event or person. So for example, when I wanted to do a paper on the man who built many of the historical homes on the Appomattox River, I didn’t read a book about him. Instead, I went to the historical society library in Richmond and had them pull everything he had ever personally written – from letters to diaries to inventories and wills. Those documents painted a more accurate picture of the man than one painted by someone else who had their personal interpretation of his life added to the mix.
So what does this have to do with Christian parenting? For Christians, our primary source document is the Bible. (I’m not ignoring the translation aspect, but that’s a more advanced level of this topic.) All other writings on the topic are considered at best a secondary source. Any book on Christianity. Any theology treatise. Any commentary. Any document written by someone and not included in the Bible is a secondary source.