“Yet, some babies die within days. How is their destiny determined?”
By making excuses. If one is faith oriented, counterarguments are always secondary. But difficult indeed it is to justify the suffering of babies. Some blame the first humans (“original sin” in Abrahamic faiths) while others blame the babies themselves (“karma” in Hinduism). The former is often scrutinized for its injustice of punishing one for the sins of the other while the latter is criticized for it insinuating cosmic cruelty instead of evoking God’s benevolence.
But the other thing is how incompatible these “faiths” are with observation. Reports from Near Death Experiences clearly disprove the “heaven/hell forever” argument. Even agnostics report encountering dead relatives. How is this possible if they were supposed to be sent to hell or get annihilated? This supports paraloka way more than the “soul” argument. I am surprised to see that even some doctors in the west are dumb enough to endorse Christianity. But perhaps there is little one can know without exposure to Dhamma?