Isaiah 54:15

Whatever trouble might come to them would not come from God as discipline, as in former times. Moreover, God’s people would be able to overcome all their opponents. This indicates that conditions for the redeemed will not be completely placid at this time, as they will be in the eternal state where nothing offensive will assail God’s people. Isaiah rather described conditions during the first part of the renovation of all things, the Millennium. It seems that assault by enemies is not just a theoretical possibility that Isaiah raised to stress the security of believers, but a real possibility for two reasons. First, the prophet spoke of this hostility at some length (Isaiah 54:15-17). Second, he already said enough about the security of the redeemed, so raising the theoretical possibility of opposition is unnecessary and disturbing.