tEi gar kariti (For by grace) este (you are, pl. ) sesOsmenoi (having been saved: perfect passive participle) dia tEs piseOs (through faith) kai touto (and that) ouk (not) ex humOn (out of you) theou (of God) to dOron (the gift).
For by means of grace you were saved and are continuing to be saved through faith, and that is the gift of God not [originating] from you.
The present perfect passive participle indicates that you were saved in the past by faith and are continuing to be saved in the present by faith. This implies that we must be believing in the past to be saved in the past, and we must be believing in the present to continue to be saved in the present.
As an example, part way through fighting a forest fire the firemen are told, "You have been protected from the fire by your fire-proof suits, and you didn't provide them yourselves, they were provided to you by the fire department."
Is their "having been protected by the fire-proof suits" transitory, or permanent? Clearly having been protected up to now depended on wearing the suits. And continuing to be in that protected state depends on continuing to wear the suits. And taking off the suit means one will lose their protection from the fire.