The Communion of Saints, follows from the fact that each of us has an immortal soul. We don't just die and have our souls lie dormant in some spiritual comma while our bodies decay. Men of Good will are a family under God our Father. We pray for the salvation of our brethren on earth, the Church Militant (fighting the good fight, running the race) and offer our sufferings and works to God to make up what is lacking in the sufferings of Jesus. The Church Suffering in Purgatory benefits from those same prayers and sacrifices, and in turn, offers prayers for us on earth. We do not sell indulgences. The Church Triumphant are the angels and saints on Heaven who behold God Face to face as the prayers of the saints reach the Throne of God.
A complete indulgence remits all one's punishment for the remission of sins; a partial indulgence is just that. Since God is eternal and we aren't, days or years are used as measure, and one must be properly dispose to gain the indulgences- as God is eternal, He has the final word on all things.
make up what is lacking in the suffering of Jesus? Seriously??
I don’t know what that doctrine is, but is it not Christian. Christ died once, for all, and cried it is finished. I did not hear it is mostly finished, or it is partially finished, or I made a good start....... Christ is all in all, His sacrifices was sufficient, and it is over. The only question is do you believe or not.