sectish
Sectarian; adherent to a sect, often to the degree of being dogmatic, insular and non-ecumenical.
rare
The only sect among Christians that is spoken of in terms— the Nicolaitan — is severely condemned. There are indications of sectish belief, against which John is supposed to labor in the first chapter of his Gospel, and Paul withstood in the Judaizing tendencies, even in a brother Apostle.
Where it comes from
From sect + -ish; perhaps after obsolete German sektisch, sektierisch or German sektiererisch.
Adapted from the Wiktionary entry sectish (CC BY-SA 4.0).