Jihad was invented by Muhammad who was political and military leader in need of big army to enable his conquest of Arabia. So when Muhammad spoke about Jihad he

Jihad was invented by Muhammad who was political and military leader in need of big army to enable his conquest of Arabia. So when Muhammad spoke about Jihad he meant it quite literaly: kill the infidels. That "spiritual struggle" interpretation was invented later, by some imams, who turned out to be better, more peaceful and compassionate human beings than the prophet himself.