חָטָא֙ יִשְׂרָאֵ֔ל וְגַם֙ עָבְר֣וּ אֶת־בְּרִיתִ֔י אֲשֶׁ֥ר צִוִּ֖יתִי אוֹתָ֑ם וְגַ֤ם לָֽקְחוּ֙ מִן־הַחֵ֔רֶם וְגַ֤ם גָּֽנְבוּ֙ וְגַ֣ם כִּֽחֲשׁ֔וּ וְגַ֖ם שָׂ֥מוּ בִכְלֵיהֶֽם׃
이스라엘이 범죄하여 내가 그들에게 명한 나의 언약을 어기었나니 곧 그들이 바친 물건을 취하고 도적하고 사기하여 자기 기구 가운데 두었느니라
Gray Matter I
The Gemara (Yevamot 47b) states that once a convert has completed the conversion process (as soon as he emerges from the mikvah), he is considered a Jew even if he later reverts to his non-Jewish lifestyle or religion. In a similar vein, the Gemara (Sanhedrin 44a) cites a verse from the book of Yehoshua (7:11) in which God proclaims, "An Israelite has sinned." The Talmud infers from this formulation that despite committing a sinful deed, the person remains a Jew ("Yisrael af al pi shechata Yisrael hu").
Kol Bo
A sinner who violated the decrees of the community, if they were not excommunicated, they are counted in a quorum of ten and they are obligated in all of the mitzvot. For thus it is said of Achan, "Israel has sinned"(Joshua 7:11) even though he sinned, he is still Israel. Therefore, they still maintain their holiness and they are not removed from the generality of Israel who are not suspected for their oaths. However, if they have been excommunicated, since they must separate themselves from the community of the diaspora, if they were to include them, what would be left of their curse what good was their decree? It is not appropriate to include them at all for they have already separated them from their community.