Yes, I can imagine that some families would find SOTW1 a little problematic (in terms of the Christian bent). Nonetheless the four books have been one of the best resources we have provided for our DCs. They provide a good overview of the sweep of world history and have given them a framework for further reading in other sources. So much better than what many kids experience in US schools - a big glob of US-focused history over and over again with little else besides.