This was a widespread (and biblical) Jewish belief. According to the book of Daniel (Dan 12:2), "many of them that sleep in the dust of the earth" would "awake" to either "everlasting life" or else "shame and everlasting contempt." Martha also seemed to be rather slow on the uptake (such as when she bustled around with "much serving" while her sister sat and listened to Jesus) and crediting her with great insight into Christian theology is questionable. So whether Lazarus' resuscitation was a pre-believing or post-believing one (or whether Lazarus believed at all), I don't think we can make an ironclad case. It is apparently the exception to the rule as Hebrews states that it is appointed once for man to die, and then the judgment.