NET
18 Children, it is the last hour, and just as you heard that the antichrist is coming, so now many antichrists have appeared. We know from this that it is the last hour.
Darby
18 Little children, it is [the] last hour, and, according as ye have heard that antichrist comes, even now there have come many antichrists, whence we know that it is [the] last hour.
KJV
18 Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time.