Regarding premillnnialism, again for example, I can accept brethren in the church who err on that subject as brethren, but I'm going to be wary of their teaching, and I'm not going to be willing to have them teach their misunderstandings, because those errors are too far reaching and ultimately destructive. The same can be said for many other doctrines, on many subjects a brother wouldn't necessarily be excluding for believing in error, but should be prevented from teaching the error either in public or in private, and the misunderstanding corrected with careful study and teaching, if it is only a misunderstanding. Church leaders, whether evangelists like Timothy or elders, have a responsibility to stop that kind of teaching in the church, and counteract it, even if the ones teaching are believers, hopefully without needlessly alienating anyone. Love as we should, and try as we might, there is such a thing as "sound teaching" and such a thing as "false doctrine." The one must be embraced, and the other refuted, and neither is limited to the basic message of the death, burial and resurrection of Christ.

1 Tim 1:3-7
As I urged you when I went into Macedonia, stay there in Ephesus so that you may command certain men not to teach false doctrines any longer 4 nor to devote themselves to myths and endless genealogies. These promote controversies rather than God's work — which is by faith. 5 The goal of this command is love, which comes from a pure heart and a good conscience and a sincere faith. 6 Some have wandered away from these and turned to meaningless talk. 7 They want to be teachers of the law, but they do not know what they are talking about or what they so confidently affirm.
NIV

Titus 1:9-12
He (an elder) must hold firmly to the trustworthy message as it has been taught, so that he can encourage others by sound doctrine and refute those who oppose it.
10 For there are many rebellious people, mere talkers and deceivers, especially those of the circumcision group. 11 They must be silenced, because they are ruining whole households by teaching things they ought not to teach — and that for the sake of dishonest gain.
NIV

2 Tim 1:13-14
What you heard from me, keep as the pattern of sound teaching, with faith and love in Christ Jesus. 14 Guard the good deposit that was entrusted to you — guard it with the help of the Holy Spirit who lives in us.
NIV

2 Tim 2:2
2 And the things you have heard me say in the presence of many witnesses entrust to reliable men who will also be qualified to teach others.
NIV

1 Tim 4:1-3
The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons. 2 Such teachings come through hypocritical liars, whose consciences have been seared as with a hot iron. 3 They forbid people to marry and order them to abstain from certain foods, which God created to be received with thanksgiving by those who believe and who know the truth.
NIV

1 Tim 4:6
If you point these things out to the brothers, you will be a good minister of Christ Jesus, brought up in the truths of the faith and of the good teaching that you have followed.
NIV

2 Tim 4:3-5
For the time will come when men will not put up with sound doctrine. Instead, to suit their own desires, they will gather around them a great number of teachers to say what their itching ears want to hear. 4 They will turn their ears away from the truth and turn aside to myths. 5 But you, keep your head in all situations, endure hardship, do the work of an evangelist, discharge all the duties of your ministry.
NIV

Titus 2:1
You must teach what is in accord with sound doctrine.
NIV