I know one offense that brings immediate excommunication and that’s abortion. But any other things? When excommunicated does that mean the faithful can’t fellowship with you? I know you have to get absolution and the excommunication lifted. And in the case of abortion issues I think most Bishops in their communities have allowed the presbyters to do this. I think anyway.
What else can get you excommunicated and how are you treated during that?
I don’t know who lifts different excommunications - some can be lifted by one’s ordinary (bishop), others have to be lifted by the Holy See. I don’t know which ones are lifted by which, but here are a few other sins that incur automatic excommunication:
breaking the seal of confession, even if under legal compulsion.
directly participating in an illicit/invalid ordination ceremony (e.g., an ordination for “womenpriests”).
impersonating a priest (leading a congregation to believe that you are a priest and, for example, confecting the Eucharist or hearing confessions)
To the bolded, yes, absolutely. Excommunication isn’t the same as shunning. And excommunication doesn’t excuse you from other obligations as a Catholic such as Mass attendance and raising your children Catholic.
In cases of automatic excommunication, most people won’t even know about it so a person wouldn’t be treated differently. There are rare public excommunications and a few cases where an automatic excommunication is made public for the good of the faithful. In those cases, the hope would be that a person’s pastor would be pulling out all the stops to get him/her back into communion with the Church.
A woman who has had an abortion is automatically excommunicated only IF she knows abortion is a sin of grave matter and goes ahead thereby committing a mortal sin AND IF she knows it carries such a penalty.
If she knows abortion is a sin of grave matter and goes ahead committing a mortal sin but does not know it carries the penalty of excommunication she is not excommunicated, just as if she does not know abortion is a sin of grave matter then she has not even committed a mortal sin by having an abortion.
Canon 1378: The pretended celebration of the Eucharist or of sacramental Confession
Canon 1388: Violation of the seal of Confession by an interpreter
Latae Sententiae Excommunication (automatic):
Canon 1364: Apostasy, heresy or schism
Canon 1367: Violation of the Sacred Species
Canon 1370: Laying violent hands on the Pope
Canon 1378: Absolution of an accomplice
Canon 1382: Episcopal consecration without authorization from the Holy See
Canon 1388: Violation of the seal of Confession by a confessor
Canon 1398: Procuring abortion