Because I don't think they really teach that. If I see a post from one of them saying exactly that, I will post a disagreement and say why I did not agree.
Why can't the Magesterium settle the question that grieves so many parents of children lost before any action could be taken for their "spiritual welfare"? I get the whole baptism is necessary thing, but maybe they got that part wrong and should recognize that baptism is something that should come after a person accepts Christ as savior not something "done" to a human being who has no understanding at all. Maybe the ordinance of water baptism is not supposed to be in the way it's done in your religion because it does not address all the aspects of it.
I believe I'm correct that some do, but it is important to be certain on each other's beliefs.
Below are the portions of the Westminster Confession of Faith (A Reformed confession of faith, in the Calvinist theological tradition) concerning predestination. I know this is the doctrine of Dr. E's Orthodox Presbyterian Church. It also applies to some other Presbyterian churches worldwide; and, with various changes, it has also been adopted by some Congregationalists and Baptists.
I think it helps immensely in these discussions to accurately get what they believe from those who believe it. If others, Reformed, on this thread include this in their articles of faith, please say so; conversely, if you/your church disagrees, please state on which parts, if you wish.
The Westminster Confession of Faith:
CHAPTER III. Of God's Eternal Decree.
III. By the decree of God, for the manifestation of his glory, some men and angels are predestinated unto everlasting life; and others foreordained to everlasting death.IV. These angels and men, thus predestinated, and foreordained, are particularly and unchangeably designed, and their number so certain and definite, that it cannot be either increased or diminished.
V. Those of mankind that are predestinated unto life, God, before the foundation of the world was laid, according to his eternal and immutable purpose, and the secret counsel and good pleasure of his will, hath chosen, in Christ, unto everlasting glory, out of his mere free grace and love, without any foresight of faith, or good works, or perseverance in either of them, or any other thing in the creature, as conditions, or causes moving him thereunto; and all to the praise of his glorious grace.
VI. As God hath appointed the elect unto glory, so hath he, by the eternal and most free purpose of his will, foreordained all the means thereunto. Wherefore, they who are elected, being fallen in Adam, are redeemed by Christ, are effectually called unto faith in Christ by his Spirit working in due season, are justified, adopted, sanctified, and kept by his power, through faith, unto salvation. Neither are any other redeemed by Christ, effectually called, justified, adopted, sanctified, and saved, but the elect only.
VII. The rest of mankind God was pleased, according to the unsearchable counsel of his own will, whereby he extendeth or withholdeth mercy, as he pleaseth, for the glory of his sovereign power over his creatures, to pass by; and to ordain them to dishonor and wrath for their sin, to the praise of his glorious justice.