Themelios (Greek: Θεμέλιος, i.e., foundation or keystone) is a peer-reviewed international evangelical theological journal that expounds on the historic Christian faith. Its primary audience is theological students, pastors and scholars. It was formerly a print journal operated by RTSF/UCCF in the UK, and it became a digital journal operated by The Gospel Coalition in 2008. Also previously it was known as the Theological Students Fellowship (TSF) Bulletin from 1951 to 1957.