I've just graduated with my BS. I have been offered a job to teach biology at a christian university prep academy. I desperately need the money, and I was raised religiously, so I expect that I will be able to do the job fairly well. However, once I get a stable financial foundation, I want to get a PhD in cell and molecular biology. Will teaching at a Christian high school basically be "career suicide" for me? Will I forget all the complex things I've already learned?
Teaching experience is a good thing. If you want to teach again after completing your PhD, the teaching experience will help you get a job.
However, I have doubts about your financial strategy. In most STEM fields, you can expect to get paid more if you have a PhD. The sooner you complete your PhD, the sooner you get the extra pay, and the more years you will keep the extra pay for. I am not knowledgeable about teacher pay, but I suspect that the best American PhD programs pay students only slightly less than typical entry level high school teaching jobs in America.
A tangential answer: it is true that if you teach X at an institution that makes X be very different from what most professional X-ists think it is, you'll risk being stigmatized. Still, don't "protest too much". But, yes, you'd like to distance yourself from Bad Science, obviously.
Also, yes, teaching high school would typically degrade one's thinking, as I've experienced myself in going from one university to another: one can become lazy by accidentally thinking that ordinary things are "fancy", because naive or uninformed people aren't aware. That is a significant trap.