Because 'saved' means we are under the rulership of Jesus, as opposed to just trying to be 'perfect' (good luck with that).
Trying to be perfect is just Shema. 100% loving on our God. It don't get you to heaven but you are still to try.
Funny thing, doing the impossible. But this is the contradictory aspect of love, trying to do that which is impossible. See God gave the Law of Shema in Deut 6:4 when at the same time He gave the Land of Milk and Honey.
And this was the greatest thing this land of plenty and relative peace. A Land where our children can be born and thrive. Only a people who wandered as the Jews did could appreciate, the people of the U.S. been spoilt for so long...
God actually said you COULD do this Law, this unfathomable and impossible Law. So then you can think it is impossible, and "good luck with that" and such, but again this is modern terp, and not Judaicterp or God-terp.
I think it is sorta like Vince Lombardi saying to give 110%. As if we could, good luck with that. See I would be the cynic thrown off the team. The go-getters don't try to analyze.
Maybe delegated to third string. WHATEVER supreme effort we give will be blessed, although no man knows where the dividing line is.
So then I just say do your best, and this in "REALLY do your best." It does not guarantee heaven, it is just our own expression of covenant.
Didache says the same thing, by the way.