I am quite happy to tell you what I believe, even unasked. For example, I do not expect to survive my death in any form. I don't expect to die only to wake up in some other world. Nor do I believe that I existed in some previous world. I only got one chance at life in any form and that chance shows up in the world as Trevor Pateman (1947 - ).
You wouldn't know that I believe this from walking past me in the street. I don't wear a badge which tells you what I believe and, as far as I know, there is no way of dressing which would convey to others that I don't believe in the immortality of the soul.
You can get an idea of what some people believe - or at least what they profess to believe - from the way they dress. People who dress as Orthodox Jews probably hold Orthodox beliefs, unless they are drug smugglers dressed up as Orthodox Jews (it has been known to work).
But I doubt that from the fact that someone is wearing a crucifix around their neck you can safely infer that they have any beliefs which they regard as specifically Christian, though they may have beliefs which coincide with Christian beliefs. Among the Ten Commandments there are several which are believed by shedloads of people who aren't in any sense Christians.
The crucifix may just have been a Christmas present from Granny. Maybe there is a sex difference: crucifixes are worn mainly by girls and women; unless they are priests, men rarely wear them.
Someone once remarked that if Christ had been born in the twentieth century, people would hang around their necks little electric chairs.
In my student days, I wore badges. I have a photograph taken at the end of my Final examinations in 1968 which shows me wearing the badge of the Vietnam Solidarity Campaign. It was probably a bit defiant, since there was a prescribed dress code for Oxford examinations - I am wearing a dark suit, a white shirt (with unprescribed frills), a white bow tie and my scholar's gown. I have taken off my mortar board. The whole lot went by the name of sub fusc. And even though I have worn it, I have no idea what sub fusc means.
Nowadays, I couldn't bear to wear a badge. I have lots of strongly held beliefs but I don't really think I should walk around with a placard, however small, which proclaims them to every unfortunate shop assistant and waiter. It's part of civility not to intrude your beliefs in contexts where they are irrelevant.
In the same way, though I have a doctorate, I don't call myself "Dr" outside of the academic contexts to which it belongs. I was reminded of this the other day when someone called me "Dr" for the first time in years.
And when I was married, I did not wear a wedding ring. Nor did my wife.
The fly in the ointment of this line of argument is the way one dresses where it is impossible not to communicate something about oneself. I dress conservatively (I often wear a tie), and some of my clothes are expensive: in winter I wear a fedora (currently a Borsalino) and they cost. (Surprisingly, perhaps, strangers often comment on my hat, even walking past me in the street).
Maybe there is a difference between taste and belief, fashion statements and ideological statements. But I admit the boundary is not always clear: think of headscarves.