Is it permissible to pray in a mosque where the ground floor is controlled by the Shi‘ah and the Sunnis control the upper floor?

My question deals with a friend of mine who was ignorantly joking. When my friend was teased by another friend he ignorantly picked up his phone out of joking and said I have to tell Allah. Then he said on the phone "Hello, Allah" as to tell Allah. I know this is incorrect but is this shirk?

Does falling into sin indicate that there is something wrong with one's 'aqeedah (belief system)?

Is it permissible to read Qur'aan while a women is having mensus (periods)?

What is the definition of gheebah and what is the ruling on it?

could you please advise us about how improve our manners, and raise our children to have good manners? As many of the scholars mentioned, they studied under their teachers for years to learn proper manners. I am very concerned because it seems that we are surrounded by bad examples and role models, and the standards of society are very low. I am a revert to Islam so I was not raised with good Islamic manners. I don't have the knowledge or training to be a very good role model. My childrens TV watching is very restricted, but they still interact with cousins and friends who pick up bad words and attitudes from TV. We also educate our children at home. But as much as we shelter them and instruct them, they seem to pick up some of the attitudes of the greater society. I am torn between whether I should continue trying to remain patient and remind them gently, or I should become more strict to enforce better behavior. We would really appreciate any advice that you could offer.

Is it true that anyone who does not accept that kuffaar are kuffaar is a kaafir himself, even if he prays, believes in the Qur'aan, and the Prophet Muhammad? If so, what is the proof for this? Can a person insist on believing that Jews and Christians can be believers and go to heaven after being shown clear evidence against this, and still be considered a Muslim?

Is it permissible to give charity to non-Muslims if they are in urgent need? Will the person who gives such charity be rewarded?

If the Muslims celebrate the birthday of the Prophet (blessings and peace of Allah be upon him), why do they not celebrate the birthday of the Prophet of Allah ‘Eesa (peace be upon him)? Is he not a Prophet who was sent from Allah, may He be glorified and exalted? I heard this idea from someone, and I know that Christmas and the celebration thereof is haraam, but I want an answer to this question. May Allah reward you with good.

A man is experiencing waswas (insinuating whispers) from the Shaytan (devil) having to do with Allah, and he is very afraid of that.

What is customary is for us to say “Blessings and peace of Allah be upon him (sall Allahu ‘alayhi wa sallam)” specifically for our Prophet Muhammad (blessings and peace of Allah be upon him); is it permissible to offer this supplication with this wording for other Prophets? Who are the only ones for whom the following phrases are to be used: may Allah be pleased with him (radiya Allahu ‘anhu), may Allah have mercy on him (rahimahu Allah), may Allah keep him safe (sallamahu Allah)? Is it permissible to offer supplication for a great scholar who strove all his life to call people to Allah and His Messenger, such as Shaykh ‘Abd al-‘Azeez ibn Baaz and other, similar contemporary scholars, when they die, by saying “may Allah be pleased with him” or “peace be upon him”?

How can we prove to non-Muslims that Islam is a tolerant and easy religion?