Karl Barth (1886-1968) is close to my heart because I did my doctoral dissertation on his theology, and I visited his hometown and grave this past summer. He was a Swiss Reformed theologian who began as a pastor. Discouraged by the popular liberal theology of his time, he wrote a commentary on the letter to the Romans, Der Römerbrief (1919, revised 1922), which unexpectedly propelled him to the center of theological discussion. His "dialectical theology" developed through the 1920s and early 1930s, and during the 1930s he was also a leading voice against Hitler and National Socialism. Ordered to leave Germany, he returned to Switzerland and, aided by his assistant and companion Charlotte von Kirschbaum, he embarked on his magnum opus, the Church Dogmatics (1933-1962), at over 9000 pages one of the longest works of systematic theology.
Thomas Merton (1915-1968) was born in France, his father was from New Zealand and his mother from the states. His mother died when he was young, and his somewhat absent father also died, and subsequently, Merton lead a life of travel and discovery, with some dark chapters of drinking and womanizing, for instance, during his Cambridge years. He came to the U.S. to study at Columbia, and the cultured and interesting but still lost young man developed an interest in Catholicism. Eventually that interest led him to become a priest and monk at Gethsemane Abbey in Kentucky. He wrote an autobiography, The Seven Story Mountain (1947) that became an unexpected best-seller. He was passionate about spirituality, monastic practice, prayer, art, world religions, and social issues. Although he died accidentally at the age of 52, he wrote many books of theology, essays, literary criticism, and poetry, as well as private journals that were eventually published.