A mamzer shall not enter the congregation of the L-rd?

[wonderfulgoy]

'An Israelite girl married to a priest, a priestly girl married to an Israelite - and she produced a daughter with him, and the daughter went and married a slave or a gentile and produced a son from him - lo, this son is a mamzer.' (Yebamot 7:5, clause III)

Then:

'Mamzerim ... are prohibited [from entering the congregation of the L-rd], and the prohibition concerning them is forever, all the same being males and females.'  (Yebamot 8: 3 clause III)

[jdl4ever]

Entering into the congregation of the L-rd refers to marrying a regular Jew.  Mamzers are not allowed to get married and have children their is one exception, if they marry each other (but this is not a good idea bec. their children will be memzerim).  Entering into the congregation of the L-rd does not mean literally that they are not Jews according to tradition just as excommunication is not literal but means that their children will die early.  Entering the congregation means that they can't get married to regular jews and are therefore excluded from the congregation.