In this section, we begin with Luther's errors as delimited in exsurge domini concerning excommunication.
23. Excommunications are only external penalties and they do not deprive man of the common spiritual prayers of the Church.
To state an excommunication is "only" an external penalty is false. Excommunication deprives one of receiving any of the Sacraments, save the Sacrament of Penance/Reconciliation.
24. Christians must be taught to cherish excommunications rather than to fear them.
Excommunication is intended to be reconciliatory, it is a corrective tool used by the Church when one has strayed from the truth and is in danger of losing their soul and/or may be endangering others of losing their souls. In one respect one could "cherish" this corrective action - but the very reason this action is being taken is because the recipient is in danger of being lost, which is something to fear! One should fear the reason excommunication is being levied upon them.
In the next section we discuss Luther's errors regarding the papacy.