In their commentary on Romans 5:18, 19th century Baptist New Testament scholars Albert Arnold and D.B. Ford write:
A few words in regard to the future condition of those dying in infancy. We scarcely need an apostle to tell us that a condemnation and death has been visited upon them on account of sin not their own; hence on account of Adam’s transgression. A part of this penalty they, in common with us all, must suffer. The great trouble respecting their case has reference to the evil that is in their hearts—their native depravity, their ‘original sin.’ With the elder Hodge, ‘we believe that the grace which is in Christ Jesus secures the salvation of all who have no personal sins to answer for.’
And the ground of our belief is the assurance that Christ who died for our fallen race, who is a propitiation for the sins of the whole world, who died for all, and who tasted death for every one, has not necessarily died in vain for any one of Adam’s descendants. To suppose that our dying infants can have no Saviour, and no participancy in his salvation, but are necessarily debarred from the benefits of Christ’s death, is to antagonize and overthrow the glorious gospel of the blessed God.
Of one thing we are absolutely certain, that our offspring, early called from earth, have no deeds done in the body to answer for, and hence will not be condemned for actual sin in the “judgment of the great day. …
–Albert N. Arnold and D.B. Ford, Commentary on the Epistle to the Romans. Philadelphia: American Baptist Publication Society, 1889. p.142. paragraphs divided solely for readability purposes; emphasis original)