+JMJ+
Two questions:
- How are we to understand “the Father who let His Son suffer”? That doesn’t sound loving or good – and when you say “for our sins”, it doesn’t sound just, either. (It sounds like you’re describing penal substitution theory, which apparently the Church condemns.)
Notice the words I used: “let His Son suffer”. It is not “made His Son suffer.” Christ Himself, out of His love for us, gave Himself to us out of His free will, and the Father let Him. If you look at
this part of the Catechism, one section is titled: “CHRIST OFFERED HIMSELF TO HIS FATHER FOR OUR SINS.” It would be best if you read the whole section.
Finally, when you say “and lets us participate”, how does this not diminish what Jesus did if He didn’t do it alone, or (referring to your Colossians quotation) if there’s suffering He didn’t experience when He did it? In other words, how are we to regard “Jesus carrying the cross” if we are the ones carrying it? (Although, Biblically speaking, it looks like Simon of Cyrene carried the cross, at least part of the way, that Jesus was too weak to carry it the whole way himself – but this is beside the point.) All these questions demonstrate that I don’t really understand your point.
(Isn’t that more than two questions?

)
As the Catechism says,
618 The cross is the unique sacrifice of Christ, the “one mediator between God and men”. But because in his incarnate divine person he has in some way united himself to every man, “the possibility of being made partners, in a way known to God, in the paschal mystery” is offered to all men. He calls his disciples to “take up [their] cross and follow [him]”, for “Christ also suffered for [us], leaving [us] an example so that [we] should follow in his steps.” In fact Jesus desires to associate with his redeeming sacrifice those who were to be its first beneficiaries. This is achieved supremely in the case of his mother, who was associated more intimately than any other person in the mystery of his redemptive suffering.
Apart from the cross there is no other ladder by which we may get to heaven.
There is no way you can diminish His Sacrifice by offering your own sacrifices to Him.
- How do you obtain confidence in your belief that you are part of Christ’s body, that reality is not one of the other possibilities I mentioned?
You didn’t forgot about my last post in your other thread, did you?
Then there is the visible difference in how virtuous people and people of vice react to the same suffering. As St. Augustine wrote:
Wherefore, though good and bad men suffer alike, we must not suppose that there is no difference between the men themselves, because there is no difference in what they both suffer. For even in the likeness of the sufferings, there remains an unlikeness in the sufferers; and though exposed to the same anguish, virtue and vice are not the same thing. For as the same fire causes gold to glow brightly, and chaff to smoke; and under the same flail the straw is beaten small, while the grain is cleansed; and as the lees are not mixed with the oil, though squeezed out of the vat by the same pressure, so the same violence of affliction proves, purges, clarifies the good, but damns, ruins, exterminates the wicked. And thus it is that in the same affliction the wicked detest God and blaspheme, while the good pray and praise. So material a difference does it make, not what ills are suffered, but what kind of man suffers them. For, stirred up with the same movement, mud exhales a horrible stench, and ointment emits a fragrant odor.
City of God, Book I, Chapter 8