The possessive is normally used when something belongs to somebody/something. Church tradition is using church as attribute of tradition: It describes tradition, in the same way family describes business in family business.
As for using the possessive with church, the Corpus of Contemporary American English has 2288 sentences containing "church's [noun]" where the noun following church's is, for example, one of the following:
The sentences containing "church [noun] are 14032. In this case the noun following church is, for example, one of the following:
Notice that church shoes is different from church's shoes, and that church hall is generally used to mean a room or building associated with a church. (Sometimes church hall is used to mean church, the building where Christians go to worship.)