GracethroughFaith, you need to check the context of at least one of your support verses. Job 25 is Bildad speaking, one of Job's detractors. It is a short chapter, so here it is:
Then Bildad the Shuhite replite:
"Dominion and awe belong to God;
he established order in the heights of heaven.
Can his forces be numbered?
Upon whom does his light not rise?
How then can a man be righteous before God?
How can one born of woman be pure?
If even the moon is not bright
and the stars are not pure in his eyes,
how much less a man, who is but a maggot --
a son of man, who is only a worm!"
That's the entire chapter. Let me answer some of his questions.
How can a man be righteous before God? Through Christ.
How can one born of woman be pure? Christ.
Is a man a maggot? No, man is a special creation in the image of God.
Bildad was having some major theological problems, in other words, and it is probably better not to take his words as some kind of support for any biblical theology.
Infant innocence is simply a fact. Sin nature is not the same as having commited a sin. A child, for a picture example, can be born blind, but he cannot stumble into something until he can at least crawl, if not walk. A child can be born with a sin nature, and all are -- but until that child is old enough to actually discern right from wrong, knowing the law (see Romans 7), then he cannot volitionally sin. And until that happens, he is covered by Christ's sacrifice, which was also for unknown and unintentional sins.
It should also be noted that even if someone is convinced that an infant, before he or she can do anything, is somehow a sinner, that is already covered by Christ who tasted death for everyone. That's in Hebrews 2. In 2 Corinthians 5 we find the same: "For Christ's love compels us, because we are convinced that one died for all, and therefore all died. And he died for all, that those who live should no longer live for themselves but for him who died for them and was raised again." (v.14-15)
Or again, in Romans 3: "This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fall whort of the glory of God AND ARE JUSTIFIED FREELY BY HIS GRACE THROUGH THE REDEMPTION THAT CAME BY CHRIST JESUS."
The subject of that sentence is all, and there is a double verb: "have sinned" and "are justified". Justification is for all. What a man chooses to do in response to that is up to him, contrary to reformed theology. That is why the Bible begs men, time and again, to seek God, to respond to Him, turn to Him and be saved. Justification and salvation are entirely different things. Justification paves the way for salvation but it is not salvation. All infants are justified, for they are part of the 'all'.
So there is a further argument concerning children and salvation, even added to the arguments already posted regarding children's angels always seeing the face of the Father and the kingdom of Heaven belonging to such as them. First, they have not commited any sin and you cannot be guilty of sin if you did not commit one. That is simple logic. Second, even if, by some perverse twist, an infant could actually sin, that sin is already covered by Christ and the infant is justified. Thus, until he or she can consciously rebel against God (again, see Romans 7), any sin they commit has not power to separate them from God, for death is separation and Paul tells us clearly in Romans 7 that until the law came to life for him, sin itself was dead. Not absent, but dead, powerless to separate him from God. So no matter at what age a child is actually capable of sinning, that sin cannot separate him from God until he is old enough to understand/comprehend the law of God and rebel against it.
So NO infants or children are lost to God. This is the key as to why He commanded them to be killed by the Israelites when the Promised Land was invaded. This is the key to why even the children before the Flood or in Sodom and the cities of the plain were killed in those catastrophes as children are today: if there is no chance for a child to grow up knowing there is a choice, God claims the child back. That is the key to understanding the discussion between Abraham and God before Sodom was destroyed. Fifty righteous men? 45? 30? The number keeps decreasing. Finally it is evident there are no righteous men in Sodom except Lot (which does not mean he was terrific, only that he was a believer in the Promise of a Redeemer, as all righteousness is in Christ), and therefore no one to teach the children something different than the evil filth they were being raised with.
And the children are God's. He took them back. It seems awful on our side of things, and totally merciful on His.