The Romans did not like the Druids or the Carthaginians for much the same reasons as I can tell. They were both very much into routine and plentiful human sacrifices. I know it is popular now to say the Druids were not this way, but all evidence to me suggests that they were. Even if everything else is danced around there is no getting around the fact that Druidic priests were in the front lines of their military conflicts.
Strabo:
'The Romans put a stop both to these customs and to the ones connected with sacrifice and divination, as they were in conflict with our own ways: for example, they would strike a man who had been consecrated for sacrifice in the back with a sword, and make prophecies based on his death-spasms; and they would not sacrifice without the presence of the Druids. Other kinds of human sacrifices have been reported as well: some men they would shoot dead with arrows and impale in the temples; or they would construct a huge figure of straw and wood, and having thrown cattle and all manner of wild animals and humans into it, they would make a burnt offering of the whole thing.'
Caesar:
'All the people of Gaul are completely devoted to religion, and for this reason those who are greatly affected by diseases and in the dangers of battle either sacrifice human victims or vow to do so using the Druids as administrators to these sacrifices, since it is judged that unless for a man's life a man's life is given back, the will of the immortal gods cannot be placated. In public affairs they have instituted the same kind of sacrifice. Others have effigies of great size interwoven with twigs, the limbs of which are filled up with living people which are set on fire from below, and the people are deprived of life surrounded by flames. It is judged that the punishment of those who participated in theft or brigandage or other crimes are more pleasing to the immortal gods; but when the supplies of this kind fail, they even go so low as to inflict punishment on the innocent.'
Tacitus:
'On the shore stood the opposing army with its dense array of armed warriors, while between the ranks dashed women, in black attire like the Furies, with hair dishevelled, waving brands. All around, the Druids, lifting up their hands to heaven, and pouring forth dreadful imprecations, scared our soldiers by the unfamiliar sight, so that, as if their limbs were paralysed, they stood motionless, and exposed to wounds. Then urged by their general's appeals and mutual encouragements not to quail before a troop of frenzied women, they bore the standards onwards, smote down all resistance, and wrapped the foe in the flames of his own brands. A force was next set over the conquered, and their groves, devoted to inhuman superstitions, were destroyed. They deemed it indeed a duty to cover their altars with the blood of captives and to consult their deities through human entrails.'
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