Albert Barnes Commentary 1 John 2:26

"These things have I written unto you concerning them that would lead you astray." — 1 John 2:26 (ASV)

These things have I written unto you concerning them that seduce you (1 John 2:26). These writings concern their character and are intended to guard you against their deceptive arts. The word seduce means to lead astray; and here it refers to those who would seduce them from the truth, or lead them into dangerous error. The apostle does not mean that they had actually seduced them, for he states in the following verse that they were still safe; but he refers to the fact that there was a danger they might be led into error.

In this context, "seduce" can also mean "deceive."