which means that we must not try to separate sinners, or even apostates, from the church. They are all to stay together until Jesus comes.

Answer:

This favorite objection is based upon a completely wrong understanding of the meaning of the parable of the wheat and the tares. Who are the “tares”? The Spirit of prophecy makes it very clear in Christ’s Object Lessons, p. 73:
“How was it with the early church? Ananias and Sapphira joined themselves to the disciples. Simon Magus was baptized. Demas, who forsook Paul, had been counted a believer. Judas Iscariot was numbered with the apostles. The Redeemer does not want to lose one soul; His experience with Judas is recorded to show His long patience with perverse human nature; and He bids us bear with it as He has borne. He has said that false brethren will be found in the church till the close of time.” (Emphasis ours. )

The interesting fact is that neither Ananias and Sapphira, nor Simon Magus, nor Demas, nor Judas – all those mentioned – were “open sinners.” They were not revealed as false to the church members until one main test proved their infidelity. They were therefore “hidden sinners,” which makes a great deal of difference.

In contrast to the Biblical examples mentioned above, the European apostasy was done in the open and was revealed to everyone; therefore, it must be classified as “open sin.” Of this category of sin, Sister White says in Christ’s Object Lessons, p. 71:

“Christ has plainly taught that those who persist in open sin must be separated from the church, but He has not committed to us the work of judging character and motive.” (Emphasis ours.)
In conclusion, the tares do not at all represent open sinners in the church. They refer to weak, erring souls among God’s people who must be carried in the love of Christ.