No where in the Bible does it indicate that Johan represents Judaism.
Some Christians, not all, like to use the fish symbol to represent that they are 'fishers of men'. By putting an emblem of a fish on their car or wearing one around their neck, they think they are following the command at Matt 28: 19-20:
"Go therefore and make disciples of people of all the nations, baptizing them in the name of the
Father and of the Son and of the holy spirit, *teaching them to observe all the things I have
commanded YOU. And, look! I am with YOU all the days until the conclusion of the system of
things.”
Think about this, who is the only religious organization that you observe that goes out to the people just as the Apostles did to share Bible truths? In Jesus Day and early Bible Times, it was not just men who went out door-to-door, but it was women and children too. Timothy was but a boy.
In Jesus Day, they were an organized group. Jesus commanded to continue doing this work "all the days until the conclusion of the system of things.” So it only reasons that God would have an organized group still today fulfilling this command which will soon be completed according to Bible prophesy.