Ambulat nobiscum, neque tamen ex nostris [est].
which would be the correct translation to> he walks among us but he is not one of us.
Ambulate Inter Nos, Sed Unus Non Est Nostrum
or
Is inter nos ambulat, sed unus nostrum non est
<edit>"Ambulate Inter Nos, Sed Unus Non Est" Nostrum with the correct sentence in Latin that is "Ambulat nobiscum, neque tamen ex nostris [est]."</edit>
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