Every one is posting but no one is answering my orginal question, I was in conversation with an Ismaili. Who said the he is Imam and direct descendent of Hazrat Ali and he has been claiming this openly. I mean their is no secracy about it. So I would request every one to please answer my original question. Thanks.
Salaam Kinnare,
If you look at the verse closely you will notice that Allah (swt) has put a condition as to whom He will bestow the convenant of Imamate to.
.....Allah said My convenant includeth not wrong doers.
Wrong doers = Original word Quran has used is 'Zalimeen'. According to the holy Quran even minor form of Shirk or disobedience to Allah (swt) count as a Zulm and one becomes a wrong doer. Now, this person that you say claim to be an "Imam", could he claim to be free from all forms of 'wrong doing' mentioned in the Quran?
Also note that Allah did not say: The unjust will not reach My covenant, because it would have implied that it was within the power of man ‑ albeit a just one ‑ to reach the status of the imamah. Rather Allah (swt) says that my convenant will not reach the wrong doers. This sentence clearly shows that getting the imamah is not within human jurisdiction, it is exclusively in the hand of Allah and He gives to whom He pleases.