They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us.
Are all in apostasy if their language and demeanor indicates they have an improper understanding of Christ?
Hebrews 10:30-31 English Standard Version
For we know him who said, “Vengeance is mine; I will repay.” And again, “The Lord will judge his people.” It is a fearful thing to fall into the hands of the living God.
And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again.
It is not for us to judge others and declare anyone unworthy of God’s gracious gift.