Were other European religions better than Christianity?

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[...] gladiatorial fights, which were a means of sacrifice to roman gods.

No.
Gladiatorial fights were first and foremost the football, soccer, or baseball of their time. A way to keep the crowds entertained, happy, and preoccupied with anything except the affairs of state. The classic misdirection m.o. of the elites.
The 'sacrifice to the Roman gods' thing, while another snippet of misdirection functioning as a fig leaf for the gladiator fights, wasn't any more important than the BS Santa story about good and bad kids, while it really is about presents and avarice.

Surely they were, but they also held a religious value.
Certainly, the roman religion was just a bastardisation of the Greek religion, with the Greeks, notably lacking such practices, but having other things to boost their egos.