Jo: "Nowhere does that suggest that Jesus meant FUTURE sins, as well. ... There is nothing in the Scripture that suggests that a person could not fall away."
No one is saying that when Jesus said "your sins are forgiven" it meant the person would never sin again. It just means that ALL of the person's sins (past, present, and future) were forgiven at once. Does Jesus have the authority to do that? I would say "YES". If Jesus had the authority to die (pay) for all of our sins at once, why doesn't He have the authority to forgive all of our sins at once.
Of course, the Bible commands us to confess our sins both to God and to one another. That is good, and we have assurance they will be forgiven of God. The real difference we have is whether or how this is tied in to salvation or not.
1 John 2:1-2 : 1 My dear children, I write this to you so that you will not sin. But if anybody does sin, we have one who speaks to the Father in our defense—Jesus Christ, the Righteous One. 2 He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.
Under what circumstances will Jesus not speak for a believer? If he hasn't confessed his latest sins yet?
Ps. 103:12 : as far as the east is from the west, so far has he removed our transgressions from us.
That is, only until the next sin?
Rom. 8:1 : Therefore, there is now no condemnation for those who are in Christ Jesus, ...
Does this mean no one is in Christ Jesus until he confesses his last sin before he dies?
One has to wonder if Jesus could look down the "corridors of time" and foresee our acceptance of Him, couldn't He look down that same corridor and still forgive a person of all their sins (past, present, and future)?
Again, you are having a problem with time. Christ's sacrifice on the cross forgives ALL men's sins potentially, the elect and the damned. But who will ASK FOR THIS FORGIVENESS? We are REQUIRED to REPENT to be forgiven. Consider the Lord's Prayer. God's forgiveness is conditional. Thus, the wicked, who do not seek God, will not be OFFERED the Lord's work. We (I hope you and I) will and be offered Christ's forgiveness. Christ's forgiveness, thus, is not applied until that time when we sin and beg His forgiveness.
Under what circumstances will Jesus not speak for a believer? If he hasn't confessed his latest sins yet?
See above. But another point to consider, my brother, is that sin is not only a legal status, but also an ontological stance. We actually suffer, our human dignity, suffers as a result of sin. We are held slaves to it. We are wounded by its effects. Thus, Christ provided His ministry of Reconciliation to HEAL us from those effects - not only to change our legal status with God, but to give us life and give it to us to the fullest (as much as possible) even here on earth.
Does this mean no one is in Christ Jesus until he confesses his last sin before he dies?
Is someone in Christ when a Christian murders or commits adultery? You be the judge. There is more to being a Christian than a name. Only those who DO THE WILL OF THE FATHER IN HEAVEN shall enter the Kingdom.
Regards