The phrase "unchanging truth" means that something is always true and cannot be changed or altered.
Sentences with «unchanging truth»
The one unchanging truth about God is that he has remained unchangingly non-existent for all of eternity. (religion.blogs.cnn.com)
I'm glad the younger generations are noticing the ridiculousness of organized religions involving inconsistencies and a clear history of evolution (of their supposed unchanging truths). (religion.blogs.cnn.com)
«If a text is good, it has value in and of itself as it refers to a higher unchanging truth. (christianitytoday.com)