From the old flock book:
postasy .
Apostasy is a standing away from, a falling away, defection,
rebellion, abandonment ; it involves teaching false
doctrines, supporting or promoting false religion and its
holidays or interfaith activities. (Deut . 13 :13, 15 ; Josh.
22 :22, ftn . ; Acts 21 :21, ftn. ; 2 Cor. 6 :14, 15, 17, 18 ;
2 John 7, 9, 10 ; Rev . 18 :4)
Celebrating a false religious holiday would be similar to
performing any other act of false worship . (Jer . 7 :16-19)