Thomas McElwain was born into a devout family in the United States in 1949. He was occupied by religious subjects from an early age and wanted to become a pastor. He studied theology and history at the Seminaire du Salève in France from 1968 to 1972, after which he continued studies in religion at Andrews University in Michigan. Already in France he was considered a rebel in terms of theology, but his expertise in languages earned him respect.
In 1974 he entered the University of Uppsala to study Biblical Languages and Ethnography. He completed a PhD degree in 1979 from the University of Stockholm with a dissertation on American Indian religious traditions, Mythological Tales and the Allegany Seneca. He has written several books and many articles on Native American religion, Christianity, Judaism and Islam.
For many years he has lectured at various universities, especially the University of Turku in Finland where he was active from 1979-1984. He was editorial secretary for the Nordic journal of comparative religion, Temenos, for five volumes. He has been on the faculty of the department of Comparative Religion as docent at the University of Stockholm since 1982.
His active participation in church work led to his ordination to the ministry in 1988. He served a Baptist missionary society full time from 1986 to 1990. He was a voting delegate to the Baptist World Alliance at its session in Zagreb in 1989, representing the Seventh Day Baptist General Conference of USA and Canada.
Following the Baptist principles of Bible study, which encourage freedom of thought and objective examination of the text, he has come to conclusions which will surprise the reader no matter what his or her religious background