I was asked last week that question and offer here a very simple answer- we Baptists don’t practice the art of expelling people from the Church any longer because
1- people living in open rebellion against God who attend a Church where the Bible is preached and biblical ethics are taught will eventually leave on their own. Guilt gets the best of them, so they either leave the Church altogether or they attend a church where the leaders are willing to turn a blind eye to their unrepentant lifestyle.
2- That is, they expel themselves. They practice what could be called self-excommunication.
There’s a Biblical explanation of this and here it is- “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 they might be made manifest, that none of them were of us.” (1Jo 2:19)
People leave the Church for, what they profess to be, a lot of reasons but in fact there are only two. Either the Church leaves them (and heads in an unscriptural direction forcing them to find another place which adheres to the teaching of Scripture) or they leave the Church because their lives do not line up with Christian doctrine.
There are two sorts of people- the sort who judge their lives by the measure of Scripture (these are the kind who find a Church where the Bible is taught and attend there), and those who judge Scripture by their lives (picking and choosing the parts they want to believe and live by and parts they don’t).
The second sort are always judging Scripture rather than allowing Scripture to judge them; and the first are always listening to the judgment of Scripture.
It’s not all that hard to know which one is the authentic Christian.