This comes down to are you a "Christian" that follows the core message of the New Testament or are you a fundamentalist Christian that thinks every word in the Bible is unquestionable truth?
And even in those two broader scopes there is debate.
I understand your frustration with Christianity Nacht, but you seem so married to disprove the letter of Christianity that you miss those who follow the spirit of it, and while I have my problems with their dogma and theology, the core tenets of the Message in the NT is solid imo.
Are muslims not muslim because they don't blow up the "infidels"? Like I said I understand your argument, but why not the vitriol for other religions that do not follow their holy writings verbatim?
Line up 100 christians and you will get 100 different theologies. They may have similar points, but none will match identically. People are too individualistic to agree 100% on just about anything as big as religion, philosophy, theology, or politics.
As far as the OP, Catholics believe unbaptized babies who die go to purgatory. I believe the Vatican issued a statement saying retarded people do not go to hell, but I could be wrong.
As far as other sects of Christianity, I was raised in the United Methodist church, and they baptize infants, as well as Presbyterians, Lutherans, Baptists (duh), and others. Non-denominational churches (which are a sort of denomination in themselves, but that's a different discussion) are about the only churches I know that refuse to baptize infants. I'm sure there may be others, but I have not encountered any. EDIT: i think Assembly of God churches do not encourage infant baptism. But I may just be assuming that because they anoint each other with oil and roll around talking in "tongues." The two practices just seem to go together in my mind.
Most Christians I know (even the fundies) argue that God only expects us to understand to our own accord (which I basically agree with, but they wouldn't agree with me) so infants and the mentally challenged would only be judged by their own capacity.
This argument is all about interpretation and personal value placed on the Christian bible.