YOU SAID:

I can't beleive it's not butter!

INTO JAPANESE

私はそれはバターではありません信じられません！

BACK INTO ENGLISH

I think it does not believe there is no butter!

INTO JAPANESE

私はそれはバターがないとは考えていないと思います！

BACK INTO ENGLISH

I think it do not believe that there is no butter!

INTO JAPANESE

私はそれはバターがないことを信じていないと思います！

BACK INTO ENGLISH

I think it do not believe that there is no butter!