It is narrated on the authority of Ibn 'Umar ('Abdullah b. 'Umar) that the Messenger of Allah (ﷺ) observed:
Verily Islam started as something strange and it would again revert (to its old position) of being strange just as it started, and it would recede between the two mosques just as the serpent crawls back into its hole. وَحَدَّثَنِي مُحَمَّدُ بْنُ رَافِعٍ، وَالْفَضْلُ بْنُ سَهْلٍ الأَعْرَجُ، قَالاَ حَدَّثَنَا شَبَابَةُ بْنُ سَوَّارٍ، حَدَّثَنَا عَاصِمٌ، - وَهُوَ ابْنُ مُحَمَّدٍ الْعُمَرِيُّ - عَنْ أَبِيهِ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ الإِسْلاَمَ بَدَأَ غَرِيبًا وَسَيَعُودُ غَرِيبًا كَمَا بَدَأَ وَهُوَ يَأْرِزُ بَيْنَ الْمَسْجِدَيْنِ كَمَا تَأْرِزُ الْحَيَّةُ فِي جُحْرِهَا " .
Sahih Muslim 146 In-book reference : Book 1, Hadith 280 USC-MSA web (English) reference : Book 1, Hadith 271 Source
When I was watching an islamophobic video(or a video against Islam) by Christian Prince. He quoted this hadith.
Well my question is what does Prophet(PBUH) mean by saying Islam started as something strange and it would again revert to being strange.