Perhaps surprisingly the Roman occupation of Britain had little initial impact on the development of the English language. Only place names like London, Bath & Chester indicate the official language of the occupiers.
It was with the arrival of Christian missionaries in the 6th and 7th centuries that significant numbers of Latin words began entering the lexicon. Latin was the lingua franca or common language of the Christian world, with the mass or service being conducted in Latin.
Other religious words like abbot, altar, apostle & candle gradually came into common use.