Life certainly does beget life. In that limited sense your “Life from life” statement is true. There's not much question that Darwin understood the concept of reproduction.
But -- this is where we differ -- it's not a demonstrated fact, and it's not a pillar of Darwin's theory, that all life (including the first life) must come from pre-existing life.
A more accurate statement would be "evolution from life," which implies two things: (1) Where there is no life, there is no evolution; and (2) Where there is reproducing life, with variation and selection, the inevitable result is evolution.
And -- one more time -- in science (as opposed to creation "science") there is no "law of biogenesis."
Very good. what we have here are attempts to conflate a dynamic process (evolution) with a specific history (biogenesis, common descent).
The specific history of life on earth seems to be common descent from a population of single celled organisms.
Evolution is a dynamic process, and does not require or demand common descent. It could very well be that millions of abiogenic events occurred, and all but one lineage was killed off or consumed by the victorious lineage.
Lineage in single celled organisms is a dubious concept. These guys can acquire DNA from individuals of different types. There are no species as we think of species in sexually reproducing organisms. You catch a cold, you've been laid.
You may not like the idea that there is such a thing called the law of biogenesis and wish to reserve an exclusive use for the term law. That's fine, but all observation in the universe of real time shows that it is necessary and regular that life begets life. We can theorize or hypothesize otherwise. Until it is disproven, it holds. I'm happy to call it the principle of biogenesis. mware makes an appropriate point: "Given the concept that we must ACCEPT all theories, we would still believe in Spontaneous Generation instead of Biogenesis." This problem is somewhat inevitable, given the scientific style handed down from Descartes dictating that we must have certainty through the microscope of doubt.
In a court of law, laws don't always hold forever. That means, its necessity is subject to conditions. Many other kinds of similar principles have restrictive application.
Science, from earliest times, has endeavored to seek out those laws that are unconditional and unrestrictive. The term used to decribe such principles is "universal." It is logically questionable whether any science has for itself an "unrestricted universal domain." Obviously what Pasteur demonstrated has a restrictive application. I hope nobody doubts that.
On the other half however, if Darwin's theory allows for life (other than first life) coming from non-life - then the tree is not fully connected; it is not "whole." In fact, it is not a tree at all, but a field of grass.
The evolutionary tree of life, common descent, relies on "life begets life" in order for it to be a continuum.
Further, if your side of the debate is tossing common descent off the table, then you are also allowing for first life by segments - or "kinds" as the YEC'ers would claim.