Taha, there are narrations which, suggest that neither of them were believers in monotheism, but there are other weak Hadiths which, say they were brought back to life to recite the kalimah and then put back to rest. Allah knows best, but scholars I've spoken to have advised to remain silent on the matter as the Prophet (SAW) himself would be really emotional on the subject.
I think my mannerism in my last post was just fine. I think I just peddled on a raw nerve?
Abu Talib was a polythiest and Allah has explained elaborately Qur'an how such people are the worse of the crops. Take Ibrahim's (AS) father for example, Allah reprimanded Ibrahim (AS) for doing du'a for him since he didn't just worship idols, but made them himself and then would put them up for auction, ROFL. Yet you're hoping Allah is pleased with Abu Talib? Are you kidding me? If you've changed your mind and are convinced he wasn't a believer then that's a positive thing, but this fundmental fact that is more important for you to ponder on.
Yazid was a tryant and villaint, no doubt. I am not singing his praises, but just mentioned the twat to make a distinction. You're underestimating the value of this kalimah. It works BOTH ways even a non-Muslim who could've been the most noble and honourable of all people for the contribution he/she made would've for humanity, but if they failed to recognise the oneness of Allah and that Mohammad (SAW) is his messenger then they're fate is eternal damnation. Similarly, a believer can be have an array of sins, but if they wholeheartedly believe in the kalimah then they will be rewarded entry to Jannah, but at a cost and condition which, is spending the sufficient amount of time that Allah has decreed in Jahanam. This also shows the justice of Allah that if a Muslim rests on his laurels that he/she knows one way or the other I'll end up in Jannah and doesn't make a sound effort to remedy their bad habits then there will be hell to pay. This is why Allah says clearly in the Qur'an he'll forgive any sin(s) even if those sins equate to the height that from the Eart to the seventh heaven, but he'll never forgive anyone if they die in the state of Kufr, particularly if they worshipped another and/or associated partners with Allah. I'm quietly sure that Shias also believe this is apart of their aqeedah. Correct me if I'm wrong.
Being an oppressor doesn't put someone outside the fold of Islam. If I'm wrong then present your evidence otherwise Yazid was bad guy, but still Muslim. There is a narration in Bukhari that suggests he maybe yet make it to Jannah, but we'll leave that topic for another day. It is ultimately for Allah to settle his affairs.