Self Replicating Patterns?
As far as I know, there is no scientific consensus on how to define "life".
What we do know, however, is that there is tremendous opportinity for creating superstition around this issue. It can also be quite lucrative to do so, which begs the question of what kind of incentive that motivates all possible permutations of the issue on how to define life.
My personal vote goes to "self replicating patterns". They can exist on a wide variety of complexity levels, with or without humanely detectable awareness. For instance clay. Or rock crystals. Both of which seem to have "purpose"; they assimilate elements from their surroundings into their structure so that they grow.
Obviously, there is a giant leap from rock crystals to complex organisms, but what they have in common is that they are self replicating patterns. In the case of the organism, though, we are talking about a composite of many different but coordinated patterns that each and own has "purpose" although in essence they are not much different from clay or rock crystal.
The point here being that "evolution" seems to me to be about organising self replicating patterns into ever more complex structures (that in and of themselves are self replicating patterns), perhaps as a function of some natural force that we have yet to identify (in the scientific sense). From the subatomic world of weirdness and to galactic clusters, natural forces organise "stuff" into patterns - and in my opinion, this is what constitutes "life".
"The idea of God is the sole wrong for which I cannot forgive mankind." (Alphonse Donatien De Sade)