As an atheist, that definition is as useless as one involving Father Christmas. If you want to define something that has the seriousness of "life" we need to use something that doesn't rely on religious dogma.
Ergo, the clear definition is missing.
What is more, "God comes and brings that person to heaven" is pretty much only applicable to a minor subset of Christianity, which only overlaps about 40% with conservatism, hardly the modal belief or even a sizable plurality. That would be Catholicism, with purgatory. Further, it isn't the most novel of beliefs. That'd be Mormonism, with its "Spirit World" reinterpretation of swedenborgianism, or potentially some theories among Baháʼí adherents.
When you use beliefs to define biological and legal processes, things get murky and edge-case-y really really quick. You shouldn't advocate for using beliefs to define biological or legal processes, especially in a pluralistic society like the US and Western democracies, but also in general. It is a hallmark of bad governance.
This doesn't mean morals and ethics have no place in law. Only that unfalsifiable beliefs shouldn't drive law or science.
A great book on this, which has been life changing for many, is "The Demon-Haunted World" by Carl Sagan: https://en.wikipedia.org/wiki/The_Demon-Haunted_World
The truth is there is no bright line. Dying is a process, not an event. So is coming into being. Personally, I don't see a zygote as a person. But a 32 week pregnancy is pretty close? Close enough that I wouldn't condone an abortion except in extreme cases.