two times; one in a church in Solo and one in Ambon.
speculations rose regarding the motif. it can be religious, politics or even terrorism.
however, since one of the bomb exploded in a church and by considering the conflict happened in Ambon in the past, most people assume that religious conflict is behind all of those bombings.
in the head of the bombers, they might think that they carry a holy mission to defend their belief. but in my opinion, they are just lunatics who tryin to get a shortcut to heaven by sacrificing other people’s life.