Ephesians 2:8

τῇ γὰρ χάριτί ἐστε σεσῳσμένοι διὰ πίστεως:

For by grace, you are saved through faith (belief):

We are focusing on ἐστε σεσῳσμένοι which literally means "you are having been saved". ἐστε means "you are" and σεσῳσμένοι means "having been saved". This is a present perfect participle. In classical greek, the greeks would use this construction to show a continuing nature of an action of a verb that completed its action in the past, but still has an affect in the present. Think of when Jesus was tempted by Satan. Jesus said, "It is written" or "It has been written". In that context, the written word had been completed in the pass, but was still having an affect during the time of the temptation. By the time koine greek came around, much of this continuous force had fallen out of use by the greek speakers and writers. With that said, this verse is one of those where it is used.

Paul is trying to show that the Ephesians were saved in the past through their faith and they were still saved at the time of the writing of the letter. That verbal "force" gets lost in translation from greek to english.

The main emphasis of this verse is right at that beginning. 

τῇ γὰρ χάριτί (For by grace)

The greek sentence is not based on sentence structure like english sentences are. If the greeks wanted to put a big emphasis on something, they would put it at the beginning of the sentence. Paul is trying to make sure that without God's grace, salvation is not possible.