It is in no way difficult for God the Almighty to bring someone to naught but the more powerful has the greater courage. Moreover, it is very essential that such people should also be there. The enemies benefit the Prophets a lot. Most of the thirty Parts of the Holy Quran were revealed because of the opponents. Had everyone been like Abu Bakr to say “Amanna wa saddaqna” (we believe and we testify the truth) only a few verses of the Holy Quran would have been revealed – and that would have been total revelation, in the case of the Holy Quran.
Just as a tree needs clean water so also it needs manure. There is none who did not have people to oppose him. A lot of divine action is based on the mischief of the opponents. It is good for a prophet to have some opponents, for, they make him pray the more and more of the mistakes are shown to the world. This is also good for his followers, for, it gives them strength of faith.
As for God the Almighty, it does not take time for Him to bring millions of people to naught but he lets the opponents exist as a matter of necessity. Wherever there is silence (no opposition) the Jamaat there does not make progress. It is not easy for every body to understand the expedient ways of God.