What was the highest position in the government of the Roman republic?

Answer: in religion it was "pontifex maximus" (roman cults), in peace Senate (senators) and in war (or in situation considered dangerous) "dictator".

Explanation: there were also situations when some gifted senators became dictators (Sulla for ex.) or "triumviratus" (government of three men) was established. There were different "triumviratus" during the Republic ... for example ... Octavianus, Marcus Antonius, Lepidus.