Of course the one true church will always be under the attack of the enemy.

Mat 5:10 "Blessed are those who are persecuted for righteousness' sake, for theirs is the kingdom of heaven.
Mat 5:11 "Blessed are you when others revile you and persecute you and utter all kinds of evil against you falsely on my account.
Mat 5:12 Rejoice and be glad, for your reward is great in heaven, for so they persecuted the prophets who were before you.

Come, Holy Spirit, fill the hearts of your faithful and kindle in them the fire of your love.