Early life 
Born in Namur (Belgium) in 1644, he joined the Society of Jesus (the Jesuits) in 1660 and first taught in the schools of Armentières, Huy and Tournai. Equipped with a thorough training in Mathematics and Astronomy he was sent, at his own request as missionary to China (1677). After a long and difficult sea journey - passing through Goa, Siam (Thailand) and Malacca - he reached Macau in 1682 just in time to observe an eclipse of the Sun (1683).
At the Chinese Imperial Court 
He was called by the aging Father Ferdinand Verbiest, who had just found himself appointed 'Vice-President of the Tribunal of Mathematics', a very important and influential post in the Chinese empire, to join him in Peking. At the death of Verbiest (1688) Thomas took his place as the main mathematician and astronomical expert of China. For twenty years he was then a close adviser to the emperor Kangxi who, beyond scientific questions, consulted him also on moral and religious matters. In 1692 he obtained an 'edict of tolerance' that gave to the missionaries almost complete freedom to preach Christianity.
The Chinese Rites Controversy 
At a time when the future of Christian faith seemed to be bright in China the Chinese Rites controversy was raging in Europe. Charles-Thomas Maillard de Tournon, a papal legate, arrived in Peking in 1705 purportedly to inquire on the orthodoxy of the Chinese rites (particularly the 'Veneration of Ancestors' ritual, accepted by the Jesuits). In fact Tournon's mind was made up. By disregarding completely Chinese customs and etiquette, he offended the emperor who had first received him well. No pleading of Antoine Thomas, then Superior of the Jesuits in China, could prevent Tournon from issuing a decree from Nanking (1707) obliging the missionaries under severe penalties to abolish those rites. A last desperate attempt of Thomas, beseeching the legate to defer the implementation of the decree till further news were received from Rome, fell on deaf ears. Antoine Thomas died soon after (1709 in Peking), and was buried close to his friend and predecessor Ferdinand Verbiest in the Jesuit cemetery of Peking.
Main work 
Synopsis mathematica, Douai, 1685.
See also 
- List of Belgians
- Religion in China
- Christianity in China
- Jesuit China missions
- Roman Catholicism in China
- Bontinck, F., La lutte autour de la liturgie chinoise au XVII et XVIIIème siècles, Louvain, 1962.
- Thomaz de Bossierre, Yves, Un Belge Mandarin à la cour de Chine, Paris, 1977.