Why is Jesus not a "madman"?

[Confused Ape]

We've only know what the Christians believed Jesus said about himself. Christianity started in the Roman Empire so the first Christians could have been influenced by Roman religion.

Roman Imperial Cult

Another element in the Roman state religion was what is generally referred to as the imperial cult. This cult regarded emperors and members of their families as gods.

While worship of a living emperor was culturally acceptable in some parts of the empire, in Rome itself and in Italy it was not. There an emperor was usually declared a 'divus' only on his death, and was subsequently worshipped (especially on anniversaries, like that of his accession) with sacrifice like any other gods.

Emperor-worship was a unifying factor in the Roman world, practiced not only by army units spread throughout the empire but also by individuals in the provinces, where there were collective imperial cult centres at places such as Lyons (Gaul), Pergamon (Asia) and (probably) Colchester (Britain).

Julius Caesar And Judea

Julius Caesar, for one, granted the Jews privileges, including freedom of worship, exemption from army service and emperor worship

Things went downhill in Judea after Julius's time but the Jews obviously knew about Roman emperors being worshipped as gods. Christianity started as a Jewish movement - as Judaism only allows for one deity, claiming that Jesus was the son of the Jewish God would have been their only way around regarding Jesus as divine.