If there was a New Testament in Hebrew and it contained the Tetragrammaton in it, how would you get rid of it? Obviously it cannot be buried next to Sifrei Torah or other Holy works.
See Gemara Gittin 45b:
R`Nahman said: We have it on tradition that a scroll of the Law which has been written by a Min should be burnt
meaning with all the shemot.
This is stated in SA YD 281, 1:
ספר תורה שכתבו אפיקורוס -- ישרף.
This concerns good contents written by bad person, so bad contents need to be even less "kadoch". No need to bury it.