You're missing my point. To them, it is logical.
To tell a muslim that it is illogical to blow themselves up in a crowd of unbelievers is akin to telling a mad person in the grips of a psychotic episode that the voices in their head are not real and they should just go home, have a nice cup of tea and get an early night.
Except, thankfully, we don't need to do this with the overwhelming majority of muslims, because they have implicitly disavowed their faith.