The Devil will attempt to use the heresy of Arminianism or Hyper-Calvinism

"Where the truth is and where, under the guidance of the Holy Spirit, the truth is being developed, there the devil will also be found working. He is subtle. If he cannot prevent the recovery of the gospel of grace, he will try to turn grace into license. If he fails to destroy the Reformed faith with the doctrine of universal grace, dependent upon the will of man - the well-meant offer - he will endeavor to prevent this faith by a denial of the serious call of the gospel to all hearers and by a questioning of the church's duty and right to bring this command to all nations and to all persons promiscuously and without distinction." - David J. Engelsma, Hyper-Calvinism and the Call of the Gospel, Pg. 184-185