at what point does life become sacred?

You are talking about values, human values, and such values vary wildly from person to person. At one end, there are people who are vegan, avoid stepping on insects, and don't use disinfectant sprays or antibacterial soaps because they don't want to unnecessarily kill even microbes. On the other end of the spectrum you have genocidal mass-murderers who would gladly start a nuclear world war if it would satisfy their religious or political ideology.

So, there is no universal, objective point at which life becomes sacred. It's a matter of opinion from one person to the next.

Life becomes sacred when it's gone or taken from you. Like that one moment just before slowly dying when you realized how amazing life truly is and how stupid you were for giving it up.

lol, life becomes sacred when it starts living.... what that means to me as verses other people though i cannot say. But to me it means that you do not go out killing things for no particular reason.