Previously posted to Rapture Forums. Posting it here for proximity.
Although it's not clearly spelled out in Scripture, I believe the issue itself is very straightforward:
1. God created man with the capacity to believe and choose right over wrong. This is what distinguishes us from every other living creature
2. Man physically reaches full mental cognizance when the brain is fully developed (age 20 and upward). God consistently uses the age of 20 in the OT as the dividing mark between accountable and unaccountable (eternally speaking). (Ex. 30:11-16, Num. 32:11) There is no age given in the NT (I believe God defaults to save any who come to Him whatever age they may be)
3. God then sets the conditions for salvation based on our ability to believe in Him. Before Christ came, it was man's faith in the living God. After Christ came, our faith must be directed at God-manifested in the flesh, Jesus the Christ, and His finished work at the Cross.
1. God could have created mankind with full mental cognition at a much earlier age (say 13 or so), but He didn't. He doesn't explain why either.
2. Does mental cognition equal maturity? Yes and no. We all mature at different speeds, but maturity does not supersede the age-standard God set forth in Scripture. IOW, you can be immature over the age of 20, but at that point, it's on your head because you have been given the tools and you chose at that point what to do with them. (We do the same with adulthood being at 18, and breaking the law at that point carries far more severe consequences than if you were say, 17).
3. The mentally incapacitated, and children up to the age of 20 (the only consistent age we have to work with) that have not yet reached that full capacity by the Rapture, will be taken up and afforded the same level of mercy as those who died before 20 receive, and have received throughout all of time.
4. After the Dispensation of the Church ends, mankind is thrust back into the conclusion of a post-Christ dispensation of Law (the conclusion of it rather). Those who enter into it must be afforded the opportunity to either receive Christ or reject Him with full mental cognition intact, or else God's manner of justice would not be perfect in sentencing them to eternal condemnation.
1. Now, if we argue that God grants unwarranted mercy to those who, for instance, such as babies and the mentally incapacitated, what then do we make that argument? Well, we could say that according to God's own word, He is longsuffering that none should perish. (Ex. 34:6, Ps. 86:15, 2 Peter 3:9) How then can some argue that God should send babies (who lack the ability to believe) as well as those who are mentally incapacitated (who also lack the ability to believe) to eternal hell-fire for something they had no way of changing?
Does that sound like God? Does that sound like any reference to God in Scripture anywhere?
Let's make the distinction, as this issue will come up, that God allows children and the mentally incapacitated to suffer all manner of evils and death in this life. That is true. That is simply part of living in a fallen world. But the first death is of far less significance than the second death.
When we speak of eternity, well, that is God's realm, and in His realm, He is just and merciful, and all of His attributes are the very epitome of perfection.
For example, would we call a judge here on earth, who takes a child guilty of (pick a crime) and sentences him/her to life in federal prison- just or cruel?
Has it happened? Sure. And we would consider this judge cruel for condemning a child who lacks not only the ability to clearly distinguish, right from wrong but also the ability to understand the consequences of right and wrong.
If we (fallen humans) can consider that judge cruel, and we build up laws to guard against things like that because we recognize the unfairness of it, how much more does God understand perfectly the issues of culpability and innocence?
2. None of us deserve salvation. If God showed us how sinful and wicked we truly are, we would crumble into an unrecoverable tailspin of grief and misery, unable to ever be useful to Him or His purposes. Thankfully, God provides that grace and mercy to us through His Son's perfect sacrifice. If God can afford us wicked people a means to salvation, how much more would HE for those who can't understand eternal ramifications?
3. If we look at the history of this throughout the Church Age, I see some major issues of corruption that spring from the death and innocence of children. We could look at the Roman Catholic's power over family through infant baptism and purgatory. We could look at Calvinism and its corrupted version of predestination. Both of these are perversions of what the Bible says, and they both seek to place religion/religious piety over Jesus' free gift of salvation and God's longsuffering nature.
1. God created mankind to be unique in our ability/capacity to both believe and choose Him over death
2. God created mankind to arrive at that mental/cognitive destination (biologically) at the age of 20 and above.
3. Can a child receive Christ, even though that child has zero understanding of eternal consequences? Absolutely. God defaults to save any who calls upon Him and He will refuse none.
4. Can a thief on a cross receive Christ, having done absolutely nothing to warrant it? Absolutely.
5. Will the Rapture be a once in mankind event that violently separates two dispensations, unleashing hell on earth? Yes
6. Would a just-God, allow a child who cannot make that eternal decision, to enter into a time when a mark will be imposed upon all, which then condemns the bearer of said mark to eternity in hell? Don't we make this same argument for why Christians can't be in the 70th Week?