Hi, I would like to clarify, the man of lawlessness had not appeared in the first century, but it was the apostacy.
Apostle Paul's point of bringing this up was to calm down the christians who had started to imagin that the day of the Lord was present. Paul told them that it will not be near until the man of lawlessness appears. That would only happen in the very few final years of this system of things. In fact the man of lawlessness has not even now appeared. But apostacy has been in the workings. Apostle Paul describes clearly what the man of lawlessness will claim and perform. It's not symbolic. It's litteral.
He will do miracles like no one else, and many will then believe he is God. He will be what is called the Antichrist.