Is the Hadith "Islam began as something strange and will return as something strange" authentic? What is its interpretation? And how does it reconcile with Allah's preservation of the Remembrance?

The Hadith (definition), "Islam began as something strange and will return as something strange, so blessed are the strangers," is authentic. Its meaning is that Islam began with few followers then spread, and it will return to a state of deficiency and imbalance, becoming few again. To face this second period of Islam's strangeness, the Prophet (peace be upon him) guided us to enjoin good, forbid evil, call to Allah, and exert all efforts in supporting His religion. The Prophet (peace be upon him) also gave glad tidings that the truth will remain manifest through a victorious group, and that Islam will reach every place. There is no contradiction between this Hadith and the verse, "Indeed, it is We who sent down the Dhikr (the Qur'an), and indeed, We will be its guardian" (15:9), for the verse speaks about the preservation of the Qur'an, while the Hadith is about the spread of Islam and the scarcity of its followers. The second period of strangeness may be what we witness today in the alienation of many Muslims from their religion.