Thanks to the help of missionaries from Tang Ruowang and Tang Ruowang in astronomy, calendar and natural science, Kangxi himself was not disgusted with Roman Catholicism, and even thought that Kangxi himself agreed with some doctrines. It is said that Kangxi also wrote to the Pope in Rome, hoping to marry the Pope's niece. However, as the ruler of a "home-world" country, it is impossible for him to fundamentally accept the concept of the church. Coupled with the "etiquette dispute" that the church later preached against China, and the opposition of the feudal literati in the imperial court to the church thought at that time, he naturally prohibited from continuing to preach. Missionaries serving in the imperial court remain in the imperial court, but they are not allowed to preach. Generally speaking, Kangxi's thoughts are useful, but useless is forbidden.
Missionary in the early Qing Dynasty is a big topic. Please refer to related books for details.