2 Peter 2:11-16 (ESV)
Whereas angels, though greater in might and power, do not pronounce a blasphemous judgment against them before the Lord.  But these, like irrational animals, creatures of instinct, born to be caught and destroyed, blaspheming about matters of which they are ignorant, will also be destroyed in their destruction,  suffering wrong as the wage for their wrongdoing. They count it pleasure to revel in the daytime. They are blots and blemishes, reveling in their deceptions, while they feast with you.  They have eyes full of adultery, insatiable for sin. They entice unsteady souls. They have hearts trained in greed. Accursed children!  Forsaking the right way, they have gone astray. They have followed the way of Balaam, the son of Beor, who loved gain from wrongdoing,  but was rebuked for his own transgression; a speechless donkey spoke with human voice and restrained the prophet's madness.
“suffering wrong as the wage for their wrongdoing. They count it pleasure to revel in the daytime. They are blots and blemishes, reveling in their deceptions, while they feast with you.
While they feast with you, I read this and I think it must be talking of Communion. So often today people think that this is the idea of Closed Communion, to stop the immoral from communing with you. No one would be able to commune if that were the case. Neither is this about looking into the hearts of people to discern whether they have faith or not. I can’t do that. And this passage brings out the futility in that.
There are reasons for closed communion. For my part I never know if one believes or not, and I find it rather futile to try and discern that. I give it no thought. My job is to proclaim the gospel and teach, baptize and teach. I don’t know what a person believes when they come to my altar, but I want to know that I have, or another pastor, has at least taught them what they should believe. Second, in the cases of gross and manifest sin where it is apparent that there is no repentance, the goal is to tell the person that this is unacceptable. You cannot continue in this behavior openly and unashamedly and still consider yourself a Christian. Christians love, and loving our neighbor we try best we can to restrain our sinful behavior which does not treat our neighbor as one for whom Christ died.
And perhaps one of the greatest and grossest of manifest sin is that of false doctrine. We do not condone the blaspheming of Christ’s good name with legalism which is at the root of all false doctrine, believe it or not even the false doctrine of libertinism. False doctrine is insidious, and is not to be ignored or looked over as not mattering at all.
But to save us from communing with people less righteous than us? No. that won’t work. The immoral will commune. The unrighteous will feast with us. We cannot be concerned about that. That is Christ’s place. It is not a matter of looking into the hearts of others.