I am afraid, lest as the serpent deceived Eve by his craftiness, your minds should be led astray from the simplicity and purity of devotion to Christ. For if one comes and preaches another Jesus whom we have not preached, or you receive a different spirit which you have not received or a different gospel which you have not accepted, you bear this beautifully. For such men are false apostles, deceitful workers, disguising themselves as apostles of Christ. And no wonder, for even Satan disguises himself as an angel of light. Therefore it is not surprising if his servants also disguise themselves as servants of righteousness; whose end shall be according to their deeds.
– 2 Corinthians 11:3-15