From a deacon:
Dear Father Z,
my parish priest is leftist and modernist (like the vast majority of priests and bishops here in ___) and always changes the words of the Missal, adding his personal opinions. His homilies are more about ___ than the Gospel. My question is: as a permanent deacon, would I sin if I went on strike and quit acting as a deacon at Mass?
I strongly advise against any cleric going on “strike.” You are ordained for the Church – it’s not a job. You are a deacon, you should always act as a deacon, whether at Mass or elsewhere.
That said, let’s make distinctions about what “acting as a deacon” means.
As a deacon, you need not function as the deacon of the Mass at every Mass you’re at. It is acceptable for you to sit in choir. Even sitting in choir, you can assist with the distribution of Holy Communion if there are not enough priests present to do so.
If you have serious and well-founded questions about the validity of the Mass being offered, you should certainly abstain from serving at it. Then you should take other steps in keeping with the last part of Redemptionis Sacramentum.
If you are reasonably sure the Mass is invalid, document what you see and in private bring your concerns to the priest. If the priest will not address your concerns, bring your concerns to the bishop with copies to the diocesan vicar for clergy, or your regional vicar. If you are still not satisfied with the response, send what you have to the Congregation for the Doctrine of the Faith.
If the questions go to liceity, but not validity, again, document your concerns and bring them to the priest in private. If that does not produce results, write to the bishop, again with copies, etc. If you’re still not satisfied with the response, write directly to the Congregation for Divine Worship.