The great news is God is building his church and when we follow him in mission we are already guaranteed to be on the winning side. It may be uncomfortable at times (and at others it's wonderful) but the end result is promised.
The day of Pentecost opened up the door to the reality of a multi-ethnic, multi-lingual church, but it took a lot of struggle and argument before the believers saw that they needed to walk through the door.
If God had not performed the miracle, the bystanders would still have understood what was going on. Perhaps they would have struggled with the odd phrase, or with the disciples rustic accents, but they could have understood.