We must not enact traditions, in addition to the Gospel, as if they are acts of forgiveness or righteousness...

We must keep in the Church the doctrine that we receive the forgiveness of sins freely for Christ's sake, through faith.  We must also keep the doctrine that human traditions are useless services and, therefore, neither sin nor righteousness should be placed in meat, drink, clothing, and like things.  Christ wished the use of such things to be left free, since He says, "It is not what goes into the mouth that defiles a person" (Matthew 15:11); and Paul says, "The kingdom of God is not a matter of eating and drinking" (Romans 14:17).  Therefore, the bishops have no right to enact traditions in addition to the Gospel, so that people must merit the forgiveness of sins, or that they think are services that God approves as righteousness. They must not burden consciences (as though it were a sin to leave such observances undone).  All this is taught by that one passage in Acts 15:9, where the apostles (Peter) say that hearts are cleansed through faith.  Then they prohibit the imposing of a yoke and show how great a danger this is, and multiply the sin of those who burden the Church.  "Why do you tempt God?" they say.  Our adversaries are not terrified even by this thunderbolt.  They defend traditions and godless opinions with violence.
~BOC, AP, XXVIII (XIV), 7-8