“Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them.”
Romans 16:17

Jesus made clear that the wicked one; the enemy, plants his offsprings in the kingdom to stunt the purposes of God:
“The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one; The enemy that sowed them is the devil… The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity; And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth.” Matthew 13:38-39, 41-42
Further emphasized in the word:
“And no marvel; for Satan himself is transformed into an angel of light. Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.” 2 Corinthians 11::14-15
He told you this so you would be aware and guard your heart; ensuring you are always found in God’s word and in his purpose for your life. Note, Jesus called them the seed of the wicked one; meaning they are wicked, purposefully deceitful and there is no segment of their hearts that can be persuaded unto righteousness; and even though they pretend to be the ministers of righteousness, their end is to sway you away from the right path- avoid them.
“…to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols. And I gave her space to repent of her fornication; and she repented not. Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds.” Revelations 2:20-22