There is a halocho that applies specifically to Krias Shma, that the Shulchon Oruch learns applies to all tefillos, which states that one has to not merge letters that are the same in separate words, per example when saying על לבבך in Krias Shma, one must leave a space between the lameds. In Havdalah we say המבדיל בין ישראל לעמים. When said properly, according to this halocho, a space must be left between the lameds. This hints that no matter how far a Jew may be removed from Yiddishkait, that Yid is still a Yid. This also goes in regards to how accepted we are by our surrounding culture, even if we are completely accepted by gentile culture to the highest degree, the fact of the matter is a Yid will never be a goy, a Yid will always be separate to some small degree. A goy can become a Yid, but that’s a discussion for another time.