Tell me something, please. What exactly do you mean when you speak of the "superabundant" merit of Christ's sacrifice? I would have thought that the perfect sacrifice would have been sufficient to its purpose, no more, no less, were I to quantify it at all, which I wouldn't. Am I misunderstanding the word? If not, I doubt an Orthodox person would even think in terms of "superabundancy" when it comes to the Incarnation.
"...the channel of connection is mercy, rather than any kind of purchase of merit for temporal suffering."
Spin that out, please. It is intriguing, Alex.
"Likewise, indulgenced work is not an addition to the suffering of Christ..."
I should think not!
"... but rather a participation in that same suffering."
Huh? You've lost me. +John Chrysostomos says that we share in Christ's death through baptism, but his suffering on the Cross, do we share that in any sense more tangibly than that all of our suffering in this life comes, ultimately, from sin, our own or those of others?
It is one of those crusty Catholic words. It originates, I believe, with St. Paul's Romans 5
16 And not as it was by one sin, so also is the gift. For judgment indeed was by one unto condemnation; but grace is of many offences, unto justification. 17 For if by one man's offence death reigned through one; much more they who receive abundance of grace, and of the gift, and of justice, shall reign in life through one, Jesus Christ. 18 Therefore, as by the offence of one, unto all men to condemnation; so also by the justice of one, unto all men to justification of life. 19 For as by the disobedience of one man, many were made sinners; so also by the obedience of one, many shall be made just. 20 Now the law entered in, that sin might abound. And where sin abounded, grace did more abound.
The word was used by Aquinas:
He properly atones for an offense who offers something which the offended one loves equally, or even more than he detested the offense. But by suffering out of love and obedience, Christ gave more to God than was required to compensate for the offense of the whole human race. First of all, because of the exceeding charity from which He suffered; secondly, on account of the dignity of His life which He laid down in atonement, for it was the life of one who was God and man; thirdly, on account of the extent of the Passion, and the greatness of the grief endured, as stated above (Question [46], Article [6]). And therefore Christ's Passion was not only a sufficient but a superabundant atonement for the sins of the human race; according to 1 Jn. 2:2: "He is the propitiation for our sins: and not for ours only, but also for those of the whole world."(Summa III.48.2 "Whether Christ's Passion brought about our salvation by way of atonement?"
Annalex: the channel of connection is mercy
What I mean is that the indulgenced work is eficacious not because we are owed a compensation for it, but because we make a plea for divine mercy through it.
do we share [the suffering of Christ] in any sense more tangibly than that all of our suffering in this life comes, ultimately, from sin
I was thinking of these two passages in particular:
For as the sufferings of Christ abound in us: so also by Christ doth our comfort abound.6 Now whether we be in tribulation, it is for your exhortation and salvation: or whether we be comforted, it is for your consolation: or whether we be exhorted, it is for your exhortation and salvation, which worketh the enduring of the same sufferings which we also suffer. 7 That our hope for you may be steadfast: knowing that as you are partakers of the sufferings, so shall you be also of the consolation
(2 Corinthians 1)
24 Who [the faithful] now rejoice in my sufferings for you, and fill up those things that are wanting of the sufferings of Christ, in my flesh, for his body, which is the church:
(Colossians 1)
The Catholic teaching is that our suffering allows us to participate in the suffering of Christ; we should distinguish between the suffering inflicted on us unvoluntarily due to sin, our own or others', and a suffering undertaken purposely to bring us closer to Christ.
Please let me know if I am not answering the question, I'll give it a better try tomorrow.