Complex sentence: Traditionally, Christianity have been considered'foreign religion' in China, with all consequences of negative connotations of foreignness in China--an attitude only started to change at the end of the 20th century.
Split into simpler sentences: Traditionally, Christianity has been considered a'foreign religion' in China, including all the negative connotations of foreignness common in China. This attitude only started to change at the end of the 20th century.