As a non-denominational Christian, I believe in Original Sin because that is what the bible teaches but I do not believe in infant baptism because it is no where taught in Scripture. We do not believe baptism in and of itself imparts any special grace or forgiveness of sin. It is not some magical incantation. It is the outward visable sign of the grace within, done in obedience to the call of the Holy Spirit on your heart and the command of the Lord. Infants are unable to understand the call nor obey the command.
What happens to children that die before coming to the age of reason? We are content to trust God’s judgement in such matters.