The Catholic Church teaches about a place called Purgatory. Purgatory, according to the Catholic Church is an intermediate state after physical death in which those destined for heaven “undergo purification, so as to achieve the holiness necessary to enter the joy of heaven.”
o Catechism 1031: “The Church gives the Purgatory to this final purification of the elect, which is entirely different from the punishment of the damned. The Church formulated her doctrine of faith on Purgatory especially at the Councils of Florence and Trent. The tradition of the Church, by reference to certain texts of Scripture, speaks of a cleansing fire.”
o Catechism 1475: “In the communion of satins, ‘a perennial link of charity exists between the faithful who have already reached their heavenly home and those who are expiating their sins in purgatory and those who are still pilgrims on earth. Between them, there is, too, an abundant exchange of all good things.’ In this wonderful exchange, the holiness of one profits others, well beyond the harm that the sin of one could cause others. Thus recourse to the communion of saints lets the contrite sinner be more promptly and efficaciously purified of the punishments for sin.”
o The Compendium of the Catechism of the Catholic Church, first published in 2005, is a summary in dialogue form of the Catechism of the Catholic Church, and it says:
What is purgatory? Purgatory is the state of those who die in God’s friendship, assured of their eternal salvation, but who still have need of purification to enter the happiness of heaven.
How can we help the souls being purified in purgatory? Because of the communion of the saints, the faithful who are still pilgrims on earth are able to help the souls in purgatory by offering prayers in suffrage for them, especially the Eucharistic sacrifice. They also help them by almsgiving, indulgences, and works of penance.
BUT to say we must atone for our sins by cleansing in Purgatory is to deny the sufficiency of the atoning sacrifice of Jesus.