Can the sin of apostasy be forgiven (and the excommunication lifted)in a normal confession or is a bishop needed? Do thoughts of apostasy entail excommunication?
Thoughts cannot be excommunicable. Period. Only external actions. Apostasy is the total repudiation of the Christian faith. It can’t be done simply by fleeting thoughts or by accident.
Please seek help for your scrupulosity and anxiety from a regular confessor and/or a counselor. Asking on internet forums will only drive your condition.
Very wise advice.
Apostasy as an act in the external forum merits automatic excommunication under the current code of canon law. This means that a thought alone does not excommunicate, but if you tell people that you no longer believe and proclaim yourself as an apostate, even in ‘private’ to a friend, that automatically excommunicates.
Check Canon 1364 of the current code of canon law:
Can. 1364 §1. Without prejudice to the prescript of ⇒ can. 194, §1, n. 2, an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication; in addition, a cleric can be punished with the penalties mentioned in ⇒ can. 1336, §1, nn. 1, 2, and 3.
Latae Sententiae means automatic excommunication. Bishops have the power to remove it, sometimes they have granted this power to parish priests, you’d have to check with the priest you intend to confess to. So many Catholics don’t even know about this penalty for these sins, you actually have to be aware of the penalty in order to have it apply to you, but all in all I think it’s an absurd practice (and should be struck from canon law), to put this kind of distress in the mind of a person who may be scrupulous and feeling as thought they might be excommunicated.
Entertaining thoughts of apostasy, while sinful, bring no special canonical censure. The action must be followed through. Moreover, we must differentiate between apostasy and heresy as well. Apostasy is abandonment of the Christian religion in favour of another religion or an opposed philosophical system. Heresy is defection from the Catholic Church into another Christian sect, such as a Protestant church.
The good news is that we’re not nearly so rigorous as Tertullian was. If one, not a cleric, religious, or academic, does follow through with apostasy or heresy, nothing is likely to happen in the way of formal censure. Repenting of that apostasy, one can return to any priest, though the pastor of the parish where one lives is most preferable. Many bishops throughout the Western world have delegated such cases reserved to them to all pastors or even to all priests, so the best thing to do is to speak to the pastor about this matter, and to seek his advice.