In the midst of a discussion with some very religious people, Jesus confronts them saying,
… The works that I do in my Father’s name bear witness about me, 26 but you do not believe because you are not among my sheep. 27 My sheep hear my voice, and I know them, and they follow me. 28 I give them eternal life, and they will never perish, and no one will snatch them out of my hand.
He is only confirming what we have heard many times before – that not everyone will believe. Even among the religious there will be deceivers, many of whom have first deceived themselves. In those days it was Jews celebrating Hanukkah, in our day it might be Christians celebrating Christmas.
In Matthew Jesus spoke of weeds growing in the wheat field and bad fish that needed to be thrown out. Paul elaborates on the same theme to the Corinthian church in 1 Cor 11.
13 For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ. 14 And no wonder, for even Satan disguises himself as an angel of light. 15 So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
Lets not be surprised when the church disappoints us or seems to be veering off track. Some of it is intentional and motivated by those who never knew Jesus to begin with. As he put it in the Sermon on the Mount,
21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’