The correct translation is "from the evil."
>"2 and that we may be delivered from the unreasonable and evil men, for the faith [is] not of all; 3 and stedfast is the Lord, who shall establish you, and shall guard [you] from the evil;" (2 Thes. 3:2-3, YLT)
Both 1st and 2nd Thessalonians are generally agreed to have been written approx. 50-51 AD. This places the time of the letters during the period when the Jews were troubling the assemblies of God. It continues the subject from 1 Thessalonians praising their faithfulness
in the face of tribulations and is a reference back to 2 Thess. 1:4-6 about the tribulation and persecutions from the Jews. The evil then of 2 Thes. 3:3 was the troublesome and painful suffering they were caused by the Jews out of Jerusalem (1 Thess. 2:14; Acts 14:2; 17:5-8, 13).
Excerpt from the Pulpit commentary makes excellent point -
"The word "evil" may be either masculine or neuter: if masculine, then it denotes "the evil one;" if neuter, then "evil" in general. There is nothing in the word itself to determine its meaning; this must be learned from the context. Most commentators (Calvin, Bengel, Olshausen, Hofmann, Macknight, Ellicott, Eadie, and Bishop Alexander) suppose that the evil one is meant; and it is so rendered in the R.V.: "Guard you from the evil one." But it is better to take the word abstractly "evil" in general, whether evil persons or evil things; as a contrast to "every good word and work" (2 Thessalonians 2:17). So Alford, Lunemann, De Wette, Jowett, Lillie. There is the same difference of opinion with regard to the words in the Lord's Prayer: "Deliver us from evil;" or "from the evil one" (R.V.). Here, also, notwithstanding the high authorities on the opposite side, we consider that our Lord's words are not limited to the evil one, but are to be taken generally - "evil" in the widest sense, as being much more forcible. 2 Thessalonians 3:3" Source: Biblehub
It is always best to keep the scriptures in the time frame in which they were written and to stay with the context / subject matter.