2 Timothy 3:1 Ch. 3 has a vivid description of apostasy (vs 1-9) But know this = NIV "mark this" "be keeping this in mind" (Wuest. Last days of what? The last days of the Jewish economy or nation. Acts 2:17. Clearly Paul was speaking of his own time, and not a time limited to "the last days of Christianity" or just a short time before the Lord's Second Coming. Perilous times = grievious time, difficult, terrible, times of stress.