Purgatory refers to the condition of purgation after death. Linked to this doctrine of 'the Communion of Saints' is the beilef that the souls in Purgatory can be aided by the prayers, indulgences and good works of living. Though there is no direct reference to Purgatory in scripture, certain texts have been taken by Doctors of the Church as a basis for the doctrine. The reference in 2 Maccabees 12:38-46, which speaks of prayer for those fallen in battle, and the New Testament texts Matthew 5:26; 12:32 and 1 Cor. 3:11-15 are commonly cited in support of the doctrine. Purgatory can be aided by the prayers, indulgences and good works of the living.

In any case, in Christian tradition there has been from the earliest centuries the practice of praying for the dead, which implies belief in the need for purgation after death. Early liturgies contain prayers for the dead. Tertullian (c.160-230) speaks of "oblations for the dead", and St Cyril of Jerusalem (c.315-386) of "supplications for those who have fallen asleep". St Augustine tells us in his 'Confessions' of a request made by his dying mother, St. Monica: "All I ask you is this, that wherever you may be you will remember me at the altar of God." That was in the year 387.

The duration of the purgation after death cannot of course be measured in relation to time as known to us on earth. After death we enter into the realm of eternity, and our present categories and conceptions cease thereafter.

The doctrine of Purgatory has been a point of controversy between the Catholic Church and the Eastern Orthodox Churches on the one hand and the Protestant Churches on the other. The Orthodox Churches see purification from the more positive aspect of maturation for one to enter heaven, whereas the Catholic position underscores purgation. The Protestant Reformers of the sixteenth century denied the need of prayer for the dead, thus rejecting what till then had been traditionally held by both Eastern and Western Churches.

Vatican II reaffirmed the traditional Catholic belief when it said: "this most sacred Synod accepts with great devotion the venerable faith of our ancestors regarding this vital fellowship with our brethren who are in heavenly glory or who are still being purified after death." (Dogmatic Constitution on the church, 51).