FAQ:Why false accusers in the last days?
(II Timothy 3:1-9 [KJV])
 This know also, that in the last days perilous times shall come.  For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy,  Without natural affection, trucebreakers, false accusers, incontinent, fierce, despisers of those that are good,  Traitors, heady, highminded, lovers of pleasures more than lovers of God;  Having a form of godliness, but denying the power thereof: from such turn away.  For of this sort are they which creep into houses, and lead captive silly women laden with sins, led away with divers lusts,  Ever learning, and never able to come to the knowledge of the truth.  Now as Jannes and Jambres withstood Moses, so do these also resist the truth: men of corrupt minds, reprobate concerning the faith.  But they shall proceed no further: for their folly shall be manifest unto all men, as theirs also was.
Because it says so in the scripture  and the scripture cannot be broken.
If he called them gods, unto whom the word of God came, and the scripture cannot be broken; (John 10:35 [KJV])
Notice also it doesn't say Christians will be false accusers, it says men will be false accusers . So beware of men. Both men that profess to be believers and those who dont.