It's easy to cite LitCharts for use in academic papers and reports.
MLA
Arn, Jackson. "Mere Christianity." LitCharts. LitCharts LLC, 12 Jan 2017. Web. 7 Mar 2021.
Chicago
Arn, Jackson. "Mere Christianity." LitCharts LLC, January 12, 2017. Retrieved March 7, 2021. https://www.litcharts.com/lit/mere-christianity.