Answering Christianity Research Center

Based on the story account, seems like Holy Spirit had left John the Baptist for quite some time. And John doesnt seem to be able to invoke Holy Spirit anymore for guidance.
Despite not able to communicate with Holy Spirit anymore, John seemed to have a strong hunch that a bird dove that he saw was infact Holy Spirit.

The people refers to the inhabitants in Arab lands.

I heard Aws say: 'I came to the Messenger of Allah [SAW] among the delegation of Thaqif and I was with him in a tent. Everyone in the tent had gone to sleep except him and I. A man came and whispered to him, and he said: Go and kill him. Then he said: Does he not bear witness to La ilaha illallah (there is none worthy of worship except Allah) and that I am the Messenger of Allah? He said: He does bear witness to that. The Messenger of Allah [SAW] said: Leave him alone. Then he said: I have been commanded to fight the people until they say La ilaha illallah. If they say it, then their blood and their wealth become forbidden to me, except for a right that is due. (One of the narrators) Muhammad said: I said to Shu'bah: 'Doesn't the Hadith contain: Does he not testify to La ilaha illallah (there is none worthy of worship except Allah) and that I am the Messenger of Allah?' He said: 'I think it is both, but I do not know.
https://www.sunnah.com/nasai/37/17


When the Messenger of Allah (ﷺ) passed away, Abu Bakr (May Allah be pleased with him) was appointed as his successor (caliph). Amongst the Arabs some men apostatised. Abu Bakr (May Allah be pleased with him) resolved to fight them. 'Umar bin Al-Khattab (May Allah be pleased with him) said to Abu Bakr: "How can you fight them when the Messenger of Allah (ﷺ) has declared: 'I have been commanded to fight people till they testify La ilaha illallah (there is no true god except Allah); and if they do it, their blood (life) and property are secured except when justified by law, and it is for Allah to call them to account." Upon this Abu Bakr (May Allah be pleased with him) said: "By Allah, I would definitely fight him who makes distinction between Salat and the Zakat, because it is an obligation upon the rich to pay Zakat. By Allah I will fight them even to secure the piece of rope which they used to give to the Messenger of Allah (ﷺ)." 'Umar (May Allah be pleased with him) said: "I realized that Allah opened the heart of Abu Bakr (May Allah be pleased with him) for fighting those who refused to pay Zakat, and I fully recognized that Abu Bakr
https://www.sunnah.com/riyadussaliheen/9/220

It is possible if the prolonged existence of Satan was not granted.

Satan appealed, “My Lord! Then delay my end until the Day of their resurrection. (15:36)

The instruction to kill street dogs in the town of Madina was only for a certain period. As for Muslims that opt to keep dogs as pet will have their daily rewards lessen.

"The Messenger of Allah said: 'whoever keeps a dog, two Qirats will be detracted from his reward each day, except a trained hunting dog, or a dog for herding livestock."
https://sunnah.com/nasai/42/16

The reason for killing dogs at that time was due to number of dogs being high in the town, and so they minimize the number of (unclean) animal especially the black ones.

"I was one of those who held up the branches from the tree away from the face of the Messenger of Allah (ﷺ) while he was delivering the Khutbah saying: 'If it were not that dogs were a nation among nations, then I would order that they be killed. So kill every one among them that is all black. There is one inhabiting a home in which they keep a dog but their deeds are decreased by one Qirat every day - except for a hunting dog, or a farm dog, or a sheep dog.'"

if you looked at the spread of Christianity throughout the globe, it began with war vessels and war planes navigating throughout regions around the globe. When they spot those foreign villages either from sea or air that do not fight them.

 The soldiers of Christs then; informed their Churches to carry their duty proselytizing.

To perform prayers and fasting in places with prolonged period of daylight will require Muslims to perform estimate of time in those places.

We asked: "O Messenger of Allah! How long will he stay on the earth?'' He said, "For forty days. One day will be like a year, one day like a month, one day like a week and the rest of the days will be like your days.'' We said: "O Messenger of Allah! Will one day's Salat (prayer) suffice for the Salat of that day which will be equal to one year?'' Thereupon he said, "No, but you must make an estimate of time and then offer Salat.'' We said: "O Messenger of Allah! How quickly will he walk upon the earth?'' Thereupon he said, "Like cloud driven by the wind (i.e., very quickly)-Hadith Muslim

they believe that everything before the beginning was unstable physics law, after big bang everything turns stable following proper physics law. no need of a Creator to be involved.

Polytheists Quraysh worshipped intermediaries deities  to Allah by invoking those idol-gods on earth. If Allah was simply the moon God, then He will not be regarded as the Most Surpeme rather one of the many intermediary god.

Also polytheists temples , churches, synagogues which are places of worship can be converted to mosques by simply removing sculptures and images and cleanse it before usage as place of prayer.
And mosque can simply be clean natural ground fenced by stones or wood.