1 John 2:28 in lieu of 26-27 is a warning as to the wiles of the spirit of the antichrist singular, Satan not seen , who works in men seen, as antichrists.
Satan, not seen insists we need a man seen to teach us . Making the promise of the Holy Spirit not seen without effect.
A good example of the father of lies working in the affairs of men is shown in action in Mathew 16:22-23 . Peter was forgiven of his blasphemy in respect to the Son of man seen. Today that kind of blasphemy against the Holy Spirit not seen cannot be forgiven. We walk by faith, the unseen, not by sight as that seen .