John,
It seems that you hold to inclusivism, which is a dangerous and unBiblical view. The fate of those who have never heard is the same as those who hear and reject. We all deserve hell and none deserve an opportunity to "accept" Christ.
Your argument regarding the fate of infants is unfounded. Infants and the mentally handicapped are different from normal people sin. The former cannot understand sin from a mental capacity. The latter sin willfully. Huge difference there.
Also, there is a direct reason why infants can be of the elect. In Romans 9 Paul says,
8 That is, it is not the children of the flesh who are children of God, but the children of the promise are regarded as descendants.
9 For this is the word of promise: "AT THIS TIME I WILL COME, AND SARAH SHALL HAVE A SON."
10 And not only this, but there was Rebekah also, when she had conceived {twins} by one man, our father Isaac;
11 for though {the twins} were not yet born and had not done anything good or bad, so that God's purpose according to {His} choice would stand, not because of works but because of Him who calls,
12 it was said to her, "THE OLDER WILL SERVE THE YOUNGER."
13 Just as it is written, "JACOB I LOVED, BUT ESAU I HATED."
14 What shall we say then? There is no injustice with God, is there? May it never be!
15 For He says to Moses, "I WILL HAVE MERCY ON WHOM I HAVE MERCY, AND I WILL HAVE COMPASSION ON WHOM I HAVE COMPASSION."
16 So then it {does} not {depend} on the man who wills or the man who runs, but on God who has mercy.
God chose Jacob before he had done any good or bad. Why? So His purpose according to His own choice might stand. God can choose to save infants and the mentally handicapped by His own choosing. However, anyone whom He saves, He has decreed would display fruit. These people cannot display fruit because they are incapable. Those who are normal and grown can display fruit. Hence, they are in a complete different situation.
Therefore, the arguments are no mutually exclusive and cannot be taken as such.
D.R.