The opponents in Ephesus are like the people predicted to come in the “later days.” Jesus also described false messiahs and prophets who would come claiming to be messengers from God. First and Second John both describe teachers with wrong views about Jesus as “antichrist.”
The idea that the “last days” have arrived in common in the New Testament, the earliest church believed that Jesus could return at any moment. In this they were correct. In 2 Thess 2 Paul teaches that in the last days there will be an apostasy, a falling away from the truth. In the last days, this falling away will be so intense that people will choose to believe the Man of Lawlessness, the Anti-Christ, rather than the truth of the gospel. Did Paul actually believe that he was living in the last days? I think that he did, but every generation of the church have had at least some people who thought they were in the last days!
But this text cannot be directly applied to any particular modern false teaching in order to declare that we are “in the end times.” Certainly Jesus can come back at any moment, and there are plenty of people teaching all sorts of things in the name of Jesus that are simply not in line with the truth. But that is the condition of all of church history!
Paul describes the opponents in Ephesus as sub-Christian. They have Christian like ideas, but when examined in the light of the truth they are in fact not Christian at all. Paul is not dealing with a group of people who have a honest difference of opinion on a theological issue. His opponents in Ephesus have rejected key elements of the gospel which separate them from the truth.
They have abandoned their faith. The verb Paul uses here (ἀφίστημι) is the same as 2 Thess 2, but also Acts 5:37 to describe a messianic pretender who led crowds astray. In Deut 7:4 it is used for turning away from God to worship other gods. These opponents have rejected the core truth of the Gospel (1 Tim 3:16) and can no longer be described as within the faith.
They follow “deceitful spirits” and hold to the “teachings of demons.” This seems like a strong polemic, the sort of thing that we would not say about an opponent today. But there are a number of Pauline texts that describe real spiritual warfare. In 1 Tim 3:6-7, for example, Paul warns that a leader in the church ought not be a recent convert, since it is possible for him to become prideful and fall into the devil’s snare.
They are hypocritical liars. Combining hypocritical and liar indicates that their teaching appears to be well-intended, but it is in fact false. This indicates that the opponents are not simply fooled into teaching something that is false, they are choosing to maintain a lie for some reason (Towner, The Pastoral Epistles, 291).
Their conscience has been seared with a hot iron. There are two ways to read this line. First the phrase may refer to someone who has told a lie so many times that they believe it, that there conscience no longer functions as it ought. They are numb to the truth, etc. Second, it is possible that this refers to being branded. The verb (καυστηριάζω) can mean sear, but it can also refer to branding someone with a hot iron. “The imagery suggests crime published with a branding mark on the perpetrator” (BDAG). In either case, their conscience has been destroyed by the “doctrine of demons” that they no longer know if they are teaching the truth or not.
I am not sure it is possible to identify the opponents from these four items alone. What is certain is that there are people in Paul’s churches in Ephesus who have defected from the Gospel in such a way that the are not Christians at all. Timothy is warned about these people and told to appoint elders who cling tenaciously to the gospel and are truly godly.