What is the ruling on one who refuses to pray behind an imam, claiming that he is an innovator (mubtadi’)?

An imam for Muslims should not be appointed from among those who openly display innovation (bid'ah) or immorality (fujoor), as the most virtuous should be put forward for imamate. If it is possible to shun an innovator-imam whose innovation is not an act of disbelief, until he repents, then that is good, provided that one does not abandon Friday prayer or congregational prayers. If refraining from praying behind him would cause the worshipper to miss Friday prayer or congregational prayers, then he should not refrain from praying behind him, except for an innovator who contradicts the Companions, as was reported concerning the Companions' prayers behind the immoral.