Belief in 12 Leaders Not In Quran.

[Rationalist]

Here is a verse about 12 leaders for the Bani Israel, but the same verse does not say to believe in the 12 leaders.

And Allah had already taken a covenant from the Children of Israel, and We delegated from among them twelve leaders. And Allah said, "I am with you. If you establish prayer and give zakah and believe in My messengers and support them and loan Allah a goodly loan, I will surely remove from you your misdeeds and admit you to gardens beneath which rivers flow. But whoever of you disbelieves after that has certainly strayed from the soundness of the way."

On the contrary for the 12ers one cannot be a momin if they don't believe in the divine appointment of the 12?

[GreatChineseFall]

Another issue is that these twelve leaders were all leaders at the same time. Which is a significant difference with their belief that there can only be one Imam at a time, like Ali became an Imam after the Prophet, Hasan being an Imam after Ali etc.

These twelve leaders were maybe the leaders of the twelve tribes at the time of prophet Musa as said in the verse:
2:60
Sahih International
And [recall] when Moses prayed for water for his people, so We said, "Strike with your staff the stone." And there gushed forth from it twelve springs, and every people knew its watering place. "Eat and drink from the provision of Allah , and do not commit abuse on the earth, spreading corruption."

And these twelve tribes were probably the descendants of the twelve sons of prophet Ya'qub taking into account the verse:
12:4
Sahih International
[Of these stories mention] when Joseph said to his father, "O my father, indeed I have seen [in a dream] eleven stars and the sun and the moon; I saw them prostrating to me."

It would be interesting to see if they think that prophet Musa was one of those leaders, or prophet Harun for that matter or both even though they would be from the same tribe.

[Rationalist]

Most of the Rafidi sects say  the divine appointment of Ali is what makes you a momin. Then they quote ahadith which states only a momin loves Ali. The issue is this ahadith does not say only those who believe in divine appointment are momins. Then if one reads the Quran there is no a single verse which connects being a believer with  the concept of divine appointment of leadership. On the contrary, the pillars such as belief in Prophethood, Salah, Zakat are there to show the connection.