The phrase "unholy thing" refers to something that is considered wicked or evil, not sacred or morally wrong. It suggests that the thing being mentioned goes against religious or ethical beliefs. Full definition
Lennon and Garant's Vatican priests mostly do boring improvisational bits in bad accents, with scenes of them going to strip clubs that show how jokes about priests doing unholy things haven't been funny or relevant in decades. (waytooindie.com)
And to do such unholy things to an acorn squash, which should be a relatively easy and delicious sell for children... We're in the midst of our own sort of «acorn squash» moment — a much - touted and highly anticipated snack menu makeover at my kids» preschool. (thelunchtray.com)
«Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?» (religion.blogs.cnn.com)