Neither excommunication nor anathemas imply the Church's condemning anyone to hell. That is the prerogative of God alone. Excommunication is a Church law, excluding a notorious sinner from the communion of the faithful (Canons 2257-2267). Its purpose is to warn the sinner of the danger he runs of incurring eternal ruin, unless he repent of his sin. The "delivering of the sinner to Satan," which we find in the Roman Pontifical, is based on the words of St. Paul, who delivered the incestuous sinner to Satan, "that his spirit might be saved in the Day of the Lord Jesus Christ" (1 Cor. 5:5; cf. 1 Tim. 1:20). . . . When St. Paul said "let him be anathema" who preaches an heretical gospel (Gal. 1:8), he did not condemn the heretic to hell, but stigmatized the willful teacher of false doctrines as a rebel against the Gospel of Christ. The Church, in the anathemas which accompany the canons of her Councils, merely imitates the example of the Apostle.

Solemn condemnation, of biblical origin, used by the Church to declare that some position or teaching contradicts Catholic faith and doctrine. An ecclesiastical censure by which one is more or less excluded from communion with the faithful. It is also called anathema, especially if it is inflicted with formal solemnities on persons notoriously obstinate to reconciliation . . . In general, the effects of excommunication affect the person's right to receive the sacraments, or Christian burial, until the individual repents and is reconciled with the Church . . . (Etym. Latin ex=, from + communicare, to communicate: excommunicatio, exclusion from a community.)

But we should note at this point that the Church has never condemned anybody, never said solemnly that so-and-so is in Hell. She can't, because that would be contrary to her mission. No Christian can, in fact, because we're supposed to judge as we would be judged. The Church can excommunicate somebody, and always has (1 Cor 5:9-12, for instance), but that's different. It means announcing publicly that this person has acted so scandalously that he cannot receive the sacraments; this allows -- even calls for -- reconciliation. And even if the person dies excommunicated, the Church prays God to forgive him.

It doesn't. Only God can condemn anyone to hell. That isn't within the Church's power, and no Catholic ever claimed it was. The Church's role is to help people to heaven by teaching and sanctifying. Of course, people can ignore the teaching and reject the grace. If they do and end up in hell, they go there by their own choice. Excommunication is a Church penalty which excludes a notorious sinner or someone grossly disobedient from the communion of the faithful. It doesn't mean the person ceases to be a Christian. its purpose is to warn the individual that he risks losing his soul unless he repents.