R’ Chaim Soloveichik was once on a train and saw a missionary working on an unlearned jew. R’ Chaim walked over and the missionary began to preach to him also. R’ Chaim answered him- j cannot be the messiah because Bar kochba was messiah. the missionary looked at him and said- What?? R akiva was wrong. no he wasnt replied r chaim. yes he was. how do you know? because Bar kochba died! answered the missionary triumphantly.
Aha!! said r’ chaim. Shtarbin iz a rayye.