Because grace is sufficient.suf•fi•cient \sə-ˈfi-shənt\ adjective[Middle English, from Latin *sufficient-, sufficiens,
from present participle of
sufficere]
(14th century)
1 a : enough to meet the needs of a situation or a proposed end
<
sufficient provisions for a month> (Or, in this case, for eternity).
b : being a sufficient condition
Because of Christ’s sacrifice, God is free to give grace to whomever He pleases, in whatever manner He pleases, and no one can dictate to Him otherwise (cf Ps 115:3; Dan 4:35).
The way prescribed for those who’s reasoning is intact is by faith; nevertheless, that doesn’t preclude God from bringing an infant into His presence,
by grace alone, at the moment of that infant’s death.
Excellent definition but if you actually read my post it was never about sufficiency but
how one gets hold of this grace if he cannot profess Jesus as Lord and Saviour.
Minor point on your first paragraph, It was not because of Christ’s sacrifice that God was free to dispense of His grace. He was free to dispense of His grace even before that

but I know what you mean. And yes, good point, God can freely dispense of His grace as He wishes and that may well extend to infants.
However, nowhere in Scripture does it say that infants will be brought to Him by grace, but that everyone else in full possession of their reasoning faculties must confess Jesus as Lord. There just was no distinction of that kind made in Scripture.
In Acts it is mentioned that they went baptising whole households. There was no mention of baptisng only grown ups of the age of reason. This is only your conclusion based on those passages. A kind of of development of doctrine by Sandusky.
For what then of those unreached by the Gospels. They have never heard Christ proclaimed to them so how can they believe (as per St Paul). Their reasoning is intact but just have not been reached by the good news (yes, because you and I are much to busy preaching to each other

)
The muslims are a very good example. They don’t know any better because they have never heard the truth about Christ.
How do they fit into this little doctrine of yours?