When reading great works, it is important to be attentive to the details that an author goes out of his way to record. Such is particularly the case with the Bible, for even the details are the inspired word of God. Thus, for example, when reading St. John’s account of the raising of Lazarus from the dead, it is noteworthy that Jesus concludes the miracle by instructing the family and friends of Lazarus to release him from the burial wrappings. John 11:44. Having raised Lazarus from the dead, could not Jesus have released the burial bands as well? He could have easily done so, but He knew that it was fitting for the family and friends of Lazarus to participate in that glorious event; and so He called for them to perform the final offices that would restore Lazarus from the grave.
That detail not only makes the account more vivid and poignant, but also (as with all of the Bible) provides a theological message as well. When people die, we entrust them to the love of God through the merits of Jesus Christ. And if a person is willing to cooperate with grace, he will get to heaven directly or through purgatory. However, as we help each other grow in grace and virtue on earth, it is only fitting that God allow the family and friends of someone who has died to help him arrive in everlasting glory. And so, we are called upon to assist those who have died on their way to heaven.
For, if a person dies in the grace of God, but imperfectly so, God will bring that person to heaven. However, because nothing attached to sin can enter into heaven, see Psalm 15:2; Rev. 21:27, a person must be purified of all sinful attachments before coming into that glorious realm. God could by His power purify the person without help from anyone else. However, God so respects human nature that He calls upon the imperfect soul to participate in that training through what we call purgatory. As with all training, such as laborious studies for mastery of a subject, practices in music and art, or boot camp in the military, such a purification involves suffering, but it is also filled with the thrill of accomplishment. And, by prayer, sacrifice and good deeds, we can help these souls, as we will be helped one day, on their final journey to the greater kingdom.