But what we do know is that Tacitus, a Roman pagan, wrote an excellent history that covered what his father-in-law Suetonius did in Britian among other things, and he writes in around 110 AD...
prepared to attack the island of Mona which had a powerful population and was a refuge for fugitives. He built flat-bottomed vessels to cope with the shallows, and uncertain depths of the sea. Thus the infantry crossed, while the cavalry followed by fording, or, where the water was deep, swam by the side of their horses. 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
People often want a narrative that there was a good religion out there, and Christianity stole its place unfairly. The truth is that all of them were bigoted and tried to destroy other religions. You don't find 21st century tolerance outside the 21 century. Not even Rome, despite the narrative recently promulgated in some quarters that it was a beacon of tolerance.