In common parlance, a BT is someone who became observant later in life. By that measurement, once a BT, always a BT. This usually means that we have to handle delicate situations with non-frum relatives, have lived a more secular life at some point, and we made a clear choice to become Torah Observant.
Another factor that makes you a BT, is that a some point you were deficient in Torah knowledge. This deficiency can be overcome, and it’s always a marvel to look at Rabbi Akiva and the 24 years he spent learning intensely, on his road to becoming perhaps the great Halachic Authority in the past 2,000 years. Of course we don’t need to learn exclusively for 24 years, but if we want to learn at high levels of Torah understanding, we have to make great efforts and put in a lot of time.
The third BT factor that comes to mind is integration into the community. To some, the ability to make people think you’re not a BT, as long as you don’t talk in learning, is a great worthwhile accomplishment. Others feel that as long as you’re a well functioning member of your community, it doesn’t matter if people know you’re a BT. Whereas others are proud to be a BT with all the accomplishment and positive growth orientation it brings. They’re not looking over their shoulders worrying about what others think.
So, are you still a BT?
Will you be comfortable if you’re known to be a BT your entire life?
Are you working on diminishing any aspects of your BT-ness?