Why does John say there are many Antichrists?

John explains in his letters that while there is an overarching spirit of Antichrist, this spirit manifests itself through many individuals who propagate false doctrines. In 1 John 2:18, he asserts that many Antichrists are already present, signifying that this is not a distant future event but an ongoing reality. These Antichrists may often appear within the framework of the church, masquerading as teachers of truth while distorting the gospel. Acknowledging this reality helps believers remain vigilant against the influence of teachings that are contrary to the core tenets of faith concerning Christ's person and work.