Colossians 2:18: Paul forbids the threskeia of angels, and so the cult of saints a fortiori
Holy Scripture does not only say in general that one God is to be worshiped and that latria is not to be given to creatures. It also forbids in particular that we give any threskeia, that is, any religious worship, to angels. And if it is not lawful to worship angels religiously, much less will it be lawful to give that worship to departed saints, since angels surpass human beings in the excellence of their nature and are not inferior to the saints in grace and glory.
The Apostle Paul expressly condemns the threskeia, or religious worship, of angels: "Let no one lead you astray who delights in humility and the worship of angels, walking in things he has not seen, that is, intruding into things he has not seen, puffed up without reason by the mind of his flesh" (Colossians 2:18). Here the Apostle forbids, without qualification, the threskeia, the religious worship, of angels.
It cannot reasonably be denied that people practice this threskeia, that is, worship angels religiously, when they build churches in honor of angels, dedicate feast days to them, invoke them solemnly in holy places, seek their patronage and protection with prayers, and bend the knee and fall to the ground as if the angels were present and watching. So, on Paul's view, such people have either been led astray by those seducers or are rashly puffed up by the mind of their flesh.
Latin
LXXIX. Verum Scriptura sacra non solum in genere dicit unum Deum esse colendum, & Latriam non esse creaturis exhibendam, sed etiam in specie vetat ne θρησκείαν ullam, id est, cultum ullum religiosum Angelis deferamus. Si autem non licet Angelos religiose colere, multo minus licebit cultum illum erga Sanctos defunctos adhibere; cum Angeli naturae praestantia homines superent, nec sint Sanctis gratia & gloria inferiores. Angelorum autem θρησκείαν, sive cultum religiosum expresse damnat Paulus Apostolus. Nemo, inquit, vos seducat volens in humilitate, & religione θρησκείᾳ Angelorum, quae non vidit ambulans, seu pedem inferens in ea quae non vidit, frustra inflatus sensu carnis suae. Ubi Apostolus simpliciter prohibet θρησκείαν, id est cultum religiosum Angelorum. Non potest autem ulla cum ratione negari illos θρησκεύειν, id est, religiose colere Angelos, qui aedes sacras in honorem Angelorum construunt, dies festos illis dicant, in locis religiosis solenniter eos invocant, & eorum patrocinium ac protectionem precibus ambiunt, ac quasi coram praesentibus atque intuentibus genua flectunt, & in terram procumbunt. Adeoque tales, secundum Pauli mentem, aut ab illis seducti sunt, aut temere sensu carnis suae inflati.