Modern Syrian Christians of Kerala (the majority Christian population here) believe that the Apostle Thomas—the one who so famously questioned Jesus—visited here in a.d. 52 and baptized their forefathers. Historians surmise that the diverse, rich trading center of Kerala may well have drawn this Palestinian Jew of the Roman Empire who wished to preach the Gospel. Thousands of churches today bear his name, their rituals and theology derived from Eastern Orthodox traditions in the liturgical language Syriac, a formation of Aramaic, the dialect Jesus—and Thomas—spoke. For decades now, the liturgical language of Kerala Christians has been Malayalam, the language of...