Reciting Bismillah Loudly in Prayer
Question

Recently I was appointed as an imam in a mosque, temporarily, and I started to lead the people in prayer. According to the best of my knowledge, there are two opinions regarding the matter of saying the Basmalah (i.e., the phrase “Bismillah Ar-Rahman Ar-Rahim (In the name of Allah, the Most Gracious, the Most Merciful)”) out loud in the prayer, and the more correct opinion is that it is not to be said out loud, so I did not say it out loud. But the people are upset about that and they have started to talk about this and complain behind my back; they are saying: “Why does this imam not say the Basmalah? He should do the same as the other imams who came before.” They also criticise me for not reciting some Surahs that are customarily recited on certain days, such as reciting Surat Al-Falaq and An-Nas in Maghrib prayer on Fridays. I am trying to ignore such matters, but I do not want to stir up trouble or be the cause of trouble being stirred up. I can easily resign from this position and delegate it to someone else, because it is a temporary post after all.
Please advise me:
Can I say the Basmalah out loud in the prayer or not? Can I recite those Surahs that they are used to hearing? Or should I give up this post altogether?
Praise be to Allah.Importance of following the Sunnah Wisdom and Kindness
We appreciate your keenness to follow the Sunnah of the Prophet (blessings and peace of Allah be upon him) in his prayer, and we appreciate your asking for the ruling on going along with the worshippers in that which they are used to. You have done well, because some of those who follow the Sunnah think that they do not need to be gentle or kind when advising people! Even if the application of the Sunnah – according to what they think is more correct – causes trouble and creates enmity and division among the Muslims, they do not hesitate to insist on applying it, no matter what the negative consequences to which that may lead. Undoubtedly this is wrong and it is not the way of the leading scholars of Ahl As-Sunnah, in the past or more recently, as we shall see below.
Reciting the Basmalah Loudly in Prayer
Undoubtedly saying Bismillah out loud in Al-Fatihah in the prayer is permissible; it is not a Bid`ah (innovation) or prohibited. But most of the time in his prayer, the Prophet (blessings and peace of Allah be upon him) did not pronounce it out loud; rather he recited it quietly.
It was narrated from Anas (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him), and Abu Bakr and `Umar (may Allah be pleased with them both) began the prayer with the words “Al-hamdu Lillahi Rabbi l-`Alamin (Praise be to Allah, Lord of the Worlds).” (Narrated by Al-Bukhari, 743)
According to a report narrated by Ahmad (12868), “They did not recite out loud the words `Bismillah Ar-Rahman Ar-Rahim (In the name of Allah, the Most Gracious, the Most Merciful).`”
This is the view of the Hanafis and Hanbalis. The Shafi`is differed from them and said that it is Sunnah to recite it out loud, even though the proven Sunnah is not to recite Bismillah out loud. But there is nothing wrong with reciting it out loud, especially if their Madhhab is that it is to be recited out loud, so as to soften their hearts.
Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
… Nevertheless the correct view is that it is not to be recited out loud, although it is prescribed to recite it out loud if that serves a definite interest. Hence it is prescribed for the imam to do that – sometimes – for example, to teach the people who are praying behind him. It is permissible for the worshippers to recite a few words out loud sometimes, and it is also permissible for a man to forego something that is preferable, in order to soften hearts and unite people, lest they be put off from what is in their best interests. For example, the Prophet (blessings and peace of Allah be upon him) decided not to rebuild the Ka`bah on the foundations of Ibrahim, because Quraysh had only recently left Jahiliyyah behind (and were new in Islam), and he was worried that they may be put off by that. He thought that the issue of uniting people and softening their hearts took precedence over the issue of rebuilding the Ka`bah on the foundations of Ibrahim. Ibn Mas`ud said, when he offered the prayer in full behind `Uthman, although he disliked that and objected to him about it, and he was questioned about that: “Dissent is evil.” Hence the imams or leading scholars, such as Ahmad and others, stated that the same applies in the case of Bismillah, and praying Witr as three continuous Rak`ahs, and other issues in which one may turn from that which is preferable to that which is permissible in the interests of softening the hearts or the obligation of teaching them the Sunnah, and so on. (End quote from Majmu ` Al-Fatawa, 22/436, 437)
He (may Allah have mercy on) also said: One may refrain from doing that which is preferable in one’s own opinion, lest the people be put off. The same applies if a man thinks that the Basmalah should be recited out loud, but he is leading some people in prayer who do not think that that is recommended, or vice versa; if he goes along with them, that is fine.  (End quote from Majmu` Al-Fatawa, 22/268, 269).
Shaykh Muhammad ibn Salih Al-`Uthaymin (may Allah have mercy on him) was asked:
What is the ruling on reciting the Basmalah out loud?
He replied:
The more correct view is that the Basmalah should not be recited out loud, and that the Sunnah is to recite it quietly, because it is not part of Al-Fatihah. But if it is recited out loud sometimes, there is nothing wrong with that. In fact some of the scholars said that it should be recited out loud sometimes, because it was recited from the Prophet (blessings and peace of Allah be upon him) that he used to recite it out loud. But what is proven from him (blessings and peace of Allah be upon him) is that he did not recite it out loud, and this is the preferred view, that he did not recite it out loud.
But if (the Imam) recites it out loud in order to soften the hearts of people whose Madhhab says that it is to be recited out loud, then I hope that there is nothing wrong with that. (End quote from Majmu` Fatawa Ash-Shaykh Ibn `Uthaymin, 13/109)
Based on that, it is permissible for you to recite the Basmalah out loud for those people, either all the time or occasionally, in order to achieve the greater interest, which is to soften their hearts, bring them together and unite them. You could also make the most of this opportunity to teach them something which is more important than practical matters of Fiqh, namely Tawhid (affirmation of the Oneness of Allah) and that which nullifies it, and shirk (association of others with Allah) and that which lead to it. Your staying and reciting the Basmalah out loud is undoubtedly better for the people than leaving them and letting your place be taken by an ignorant imam who may mislead the people, lead them into ignorance and divert them from sound Islamic knowledge.
Reciting certain Surahs and verses in certain prayers
There is nothing wrong with always reciting certain Surahs and verses in certain prayers, in two cases:

If it is proven that it is prescribed to always recite them in certain prayers, such as Surat As-Sajdah and Al-Insan in Fajr prayer on Friday. Based on that, there is nothing wrong with always reciting these prayers in Fajr every Friday.
When there is no proof that it is prescribed to always recite them, such as if the Imam always recites the final verses of Surat Al-Baqarah in Maghrib. The Sunnah is that it is not prescribed to always do that, because that is contrary to the practice of the Prophet (blessings and peace of Allah be upon him), which was to vary the Surahs recited  and lest the ignorant think that this was recommended – let alone obligatory – in every Maghrib prayer.

When to prioritise unity over strict adherence
Even though this is the Sunnah, there is no reason why you should not recite what they are used to and always do that for a while, in order to unite the worshippers and not cause division among them, and in order to close the door to any leader of Bid`ah who may seek to misguide them, and in order to endear you and the methodology that you follow to them, so that you may teach them to love the Sunnah and act in accordance with it. With the passage of time, you will be able to phase out that continual practice, as other seekers of knowledge have done in similar cases with worshippers who go against the Sunnah.
For more details, please see the following answers: 22186, 21241
And Allah knows best.