For years those involved with Judaism have used phylacteries. This is basically a box strapped around the forehead that contains pieces of scripture. There are probably several reasons these boxes are worn. Some might feel this helps them spiritually to remember their relationship to the scriptures. Others probably from simple tradition wear the phylactery. Still others wear it for prestige or to "be seen of men".
Many Christians have probably invented similar things to phylacteries. Some may have worn the phylactery for similar purposes. Others might wear robes. Others might decide everyone in their group wears the same style clothing. You can certainly think of religious groups who have decided to do this very thing.
Even though Christians do not wear phylacteries of this type nature, we in a since each have a "phylactery". This would be our "communication" according to the King James Version. This is the interaction we have with other people or our way of life. It would include speech, attitude, and so on.
Although you don't have a box strapped to your forehead, when people look at you they can tell your relationship to the scriptures. They can see if you are moral or immoral. They know if your speech "betrays you".
It is possible that a Christian has contacts that do not know he is a Christian. He has never had or taken the time to talk to these people. However, surely no Christian is thought of as wordly by those who meet him every day. His "phylactery" would not allow such to happen.
Strive to be clothed with righteousness and to have "put on Christ". Many songs suggest this concept. "Let the beauty of Jesus be seen in me." "We are the only Bible, the careless world will read." "Thou art the potter, I am the clay."