Ijtaba, all the Prophets who succeeded Moses in Bani-Israel, tried to save Bani-Israel, but at the end Bani-Israel was not saved. Few believed in the true religion as ought it to believed in.
Even during Dawood's time, and Sulaiman, they rebelled, despite true Prophets ruling them. They follow other chiefs and scholars, and attributed falsehood to Dawood and Sulaiman.
This was to the extent that Bani-Israel totally left their religion till Elyas called them back to the true God by making a stand down miracles against the false Prophets of Baal who could not do what Elyas did.
The dark forces never rest, and we can't expect them to. What we can do is foremost take responsibility and enjoin the truth despite how much people hate it and even if it leaves us with hardly anyone to accompany us in our journey.
The Prophets all strove to ready people for Mohammad, but the books were hidden or corrupted, the truth hidden and so they didn't prepare people for Mohammad.
Most Messengers were rejected and weren't supported.
Imam Hussain as a navigator and Captain tried to lead the umma to safety, to justice, to the truth, to the beauty of God's face and religon, but they turned away.
The Imams (as) never were in the same position again, that is why they didn't rise with the sword.
Yes the religion remained strong in the sense the truth was apparent, the truth became manifest, the true interpretation of Quran became clear and manifest.... and to this day despite people holding on to innovations, there is a way to clarity and truth if a person comes to Quran and Ahlulbayt (as) thirsty for wisdom and humble to their words.
In this sense, unlike other times when Islam disappeared and became near impossible to find and see the truth, in this age, with what has been left from the family of Mohammad and family of Ali, there is a way to tranquility and peace, but it must be all found in Quran just as the successor of Sulaiman all his knowledge was from the book, so must we refer all ahadith back to the book so that we see it in Quran and in a better more eloquent manner in Quran.
The knowledge of a person who brought Balqis' throne in a twinle of an eye, per Quran, was all from the book. The book has the remembrance, it says so itself, and so loving Mohammad is a remembrance, and Mohammad is a remembrance, and so if you come to Quran thirsty you should be able to see everything in the Shariah with the help of the Sunnah explanation of the Rasool and the Imams.