This is a clear proof of Shia understanding of Imamah

[shiaali]

And (remember) when his Lord tried Abraham with (His) commands, and he fulfilled them, He said: Lo! I have appointed thee a leader for mankind. (Abraham) said: And of my offspring (will there be leaders)? He said: My covenant includeth not wrong-doers. (albaqarah 124)

Why sunni still won't believe that we always need appointed imam?

[Rationalist]

The reason is according to your books 9 of the imams did taqiyyah on the matter of the Caliphate.

[Khaled]

And (remember) when his Lord tried Abraham with (His) commands, and he fulfilled them, He said: Lo! I have appointed thee a leader for mankind. (Abraham) said: And of my offspring (will there be leaders)? He said: My covenant includeth not wrong-doers. (albaqarah 124)

Why sunni still won't believe that we always need appointed imam?

And the foremost to embrace Islam of the Muhajirun (those who migrated from Makkah to Al-Madinah) and the Ansar (the citizens of Al-Madinah who helped and gave aid to the Muhajirun ) and also those who followed them exactly (in Faith). Allah is well-pleased with them as they are well-pleased with Him. He has prepared for them Gardens under which rivers flow (Paradise), to dwell therein forever. That is the supreme success. [At-Tawba:100]

Why do Shi'is still not believe that we are supposed to follow the Muhajiroon and the Ansar?

[shiaali]

I am not a 12 imam shia. Sahaba are to be followed but not on everything, they made mistakes including in succession issue, but the ayat is proof that we have to have Allah appointed leader from Ibrahim AS progeny

[Khaled]

I am not a 12 imam shia. Sahaba are to be followed but not on everything, they made mistakes including in succession issue, but the ayat is proof that we have to have Allah appointed leader from Ibrahim AS progeny

Who were the Imams from the progeny of Ibrahim عليه السلام?  Were they only from the descendants of Ishaq عليه السلام or were they also from the descendants of Ismail عليه السلام as well?

Also, what kind of Shi'a are you if you don't mind me asking?

[Hani]

Why sunni still won't believe that we always need appointed imam?

The verse you quoted, It doesn't say "always" so your conclusion is incorrect.

[Ibn Yahya]

Explain to me then why Khomeini and Shirazi, who pretty much are at opposite ends when it comes to Shi'ism, both believed that there should be a Shurah held amonger the Fuqaha to elect the Wali al-Amr? Is not the Faqih of the Islamic State the Leader of the Muslims according to them?

[Rationalist]

I am not a 12 imam shia. Sahaba are to be followed but not on everything, they made mistakes including in succession issue, but the ayat is proof that we have to have Allah appointed leader from Ibrahim AS progeny

Okay if you are not a Dozener who is the imam after Imam Hussain ?

[Rationalist]

I am not a 12 imam shia. Sahaba are to be followed but not on everything, they made mistakes including in succession issue, but the ayat is proof that we have to have Allah appointed leader from Ibrahim AS progeny

Where did you ? If the sahaba made a mistake by not giving Ali the Calipahate immediately after the Prophet (pbuh) it is  because they wanted a break from the Ummawi and Hashimi conflicts.
The people of Kufa gave Imam Ali (as) with the assurance that they will back him in wars, but in reality they betrayed him. Even in the aftermath of all of this those who gave the Ahlul Bayt bayah did not commit to the Imams in the long run.

I hear many 12ers today telling me that they would give their lives for the imams. However, what these 12ers fail to understand is giving life is not something that happens immediately. The enemies of Ahlul Bayt made the people of Kufa suffer. They would gang up on them life a wolf pack and torture the supporters of ahlul bayt till they gave up. They would put terror in their hearts. This war was a long term war. Even for the Mahdi, don't expect miracles. The sahaba witnessed these wars, and they said lets take a break from all of this. What is the point of giving bayah when it is difficult to carry on the responsibilities which comes in supporting the ahlul bayt?

[Abu Ammar]

And (remember) when his Lord tried Abraham with (His) commands, and he fulfilled them, He said: Lo! I have appointed thee a leader for mankind. (Abraham) said: And of my offspring (will there be leaders)? He said: My covenant includeth not wrong-doers. (albaqarah 124)

Why sunni still won't believe that we always need appointed imam?

'Oh David! Verily, we have placed you as a successor on earth, so judge between men in truth and follow not your desire for it will mislead you from the path of Allah. Verily, those who wander astray from the path of Allah (shall) have a severe torment, because they forgot the day of reckoning'

Surah Saad Verse 26
[38:26]

If the Imams and Prophets are infallible; then why does Allah say to Prophet Dawud (AS) '...follow not your desire for it will mislead you from the path of Allah...'? The verse then explains that following ones desire will lead to the hell fire i.e. it is a sin.

If Prophet Dawud (AS) is indeed infallible, then there is no need to warn him if this deed.

Therefore the interpretation of the verse you have quoted cannot be true, as the verse I have given clearly shows that leaders that Allah appoints are still warned of sin.

[Abu Ammar]

Also, the end of the verse you have quoted says

...My covenant includeth not wrong-doers. (albaqarah 124)

By your 'black & white' interpretation, then any Mu'min (believer) is deemed a wrong-doer for the simple reason that he is NOT infallible.

So essentially; if someone is not infallible, then he is by default a wrong-doer (Dhaalim).
So Ammar Ibn Yasser (RA) cannot rule a State because he is a wrong-doer (since he is not infallible).

This is obviously a false interpretation.