In D&C 19:16-17 it mentions that if Christ doesn’t take our sins upon him then we must suffer for them ourselves. Since kingdom progression is not possible what is the purpose of this suffering? What does it accomplish? What happens if we say no?
There are varying opinions, thoughts, and theories surrounding the possibility of progression between kingdoms; however, scriptures from our standard works appear to state that there will be no progression between heavenly kingdoms (Telestial, Terrestrial, and Celestial). The scripture you have shared, “But if they would not repent they must suffer even as I,” specifies that if we do not repent then we will suffer even as Christ, which suffering caused him to bleed from every pore (Needless to say the suffering was great). What then does this accomplish?
The first aspect this would accomplish is honoring heavenly laws. There is an eternal law which is fixed, which acted upon the sons and daughters of God the moment Adam and Eve partook of the forbidden fruit. In correlation with this law, a law of justice, mercy was granted unto man if they would accept it. Mercy can only come in and through the atonement of Jesus Christ. A couple of verses in our scriptures I love specify how Christ is our advocate with the Father (Doctrine and Covenants 45:3-5)
If we reject our Advocate, by our own personal choice, then this eternal law of Justice will act upon us, and we will suffer the consequences of our chosen lifestyle. We will endure the suffering we have caused ourselves, and we will be assigned to our glory that we chose to live. Our personal suffering, if we did not choose Christ, does not remove the consequence of heavenly laws. These laws enact upon us; whereas, through Christ, a medium was given that we might not suffer and that we might return to the presence of God.
I am sorry, I don’t understand your last question clearly; however, I will answer according to how I understand it. What we say, “yes” or “no” does not change heavenly law. If we say “yes” the law still enacts upon us. If we say “no” the law still enacts upon us. It would be similar to breaking a temporal law, and then telling the judge or the officer, “No, I will not suffer the penalty of law.” We have Youtube and other videos clearly showing how well this turned out for them. Our decision, our choice of consequence ended the moment we broke the law. The same with eternal/heavenly laws.
This is why we read in scriptures,
“And now, as I said unto you before, as ye have had so many witnesses, therefore, I beseech of you that ye do not procrastinate the day of your repentance until the end; for after this day of life, which is given us to prepare for eternity, behold, if we do not improve our time while in this life, then cometh the night of darkness wherein there can be no labor performed.” (Alma 34:33)
“And now, my brethren, I wish from the inmost part of my heart, yea, with great anxiety even unto pain, that ye would hearken unto my words, and cast off your sins, and not procrastinate the day of your repentance;” (Alma 13:27)
“But behold, your days of probation are past; ye have procrastinated the day of your salvation until it is everlastingly too late, and your destruction is made sure; yea, for ye have sought all the days of your lives for that which ye could not obtain; and ye have sought for happiness in doing iniquity, which thing is contrary to the nature of that righteousness which is in our great and Eternal Head.” (Helaman 13:38)