First of all we read what the clear Quranic verse says:
And [mention, O Muhammad], when Abraham said to his father Azar, “Do you take idols as deities? Indeed, I see you and your people to be in manifest error.” [6:74]
Now let us present authentic shia report which confirms our belief:
علي بن إبراهيم، عن أبيه، عن ابن أبي عمير، عن هشام بن سالم، عن أبي أيوب الخزاز، عن أبصير، عن أبي عبدالله (ع): أن آزر أبا إبراهيم (ع) كان منجما لنمرود ولم يكن يصدر إلا عن أمره فنظر ليلة في النجوم فاصبح وهويقول لنمرود: لقد رأيت عجبا، قال: وما هو؟ قال: رأيت مولودا يولد في أرضنا يكون هلاكنا على يديه ولا يلبث إلا قليلا حتى يحمل به، قال: فتعجب من ذلك وقال: هل حملت به النساء؟ قال: لا، قال: فحجب النساء عن الرجال فلم يدع امرأة إلا جعلها في المدينة لا يخلص إليها ووقع آزر بأهله فعلقت بإبراهيم (صلى الله عليه وآله) فظن أنه صاحبه فأرسل إلى نساء من القوابل في ذلك الزمان لا يكون في الرحم شئ إلا علمن به فنظرن فألزم الله عزوجل ما في الرحم [إلى] الظهر فقلن،: ما نرى في بطنها شيئا وكان فيما أوتي من العلم أنه سيحرق بالنار ولم يؤت علم أن الله تعالى سينجيه، قال: فلما وضعت أم إبراهيم أراد آزر أن يذهب به إلى نمرود ليقتله، فقالت له امرأته لا تذهب بابنك إلى نمرود فيقتله
‘Ali ibn Ibrahim al-Qummi from his father from Ibn Abi ‘Umayr from Hisham ibn Salim from Abu Ayyub al-Khazzaz from Abu Baseer from Imam abu ‘Abdullah (as): Azar the Father of Ibrahim (as) was an astrologer working for the king al-Namrud, one night he observed the stars and in the morning he went to al-Namrud telling him: “I have seen something strange” he said: “What is it?” he said: “I saw a newborn child that will be born in our lands, our destruction will be by his hands, his mother will soon become pregnant with him.” so he was shocked by this and asked him: “Are any of the women currently pregnant with him?” he said: “No”, so he isolated all the women from the men however Azar had slept with his wife and she carried Ibrahim (as), he thought that he was the one so he sent after some women from the tribes and they would know if there were any babies in the womb but Allah concealed Ibrahim (as) so that they couldn’t see him, they said: “We see nothing in her womb”, He was given knowledge that he shall be burned in the fire but he had no knowledge that Allah will save him, when Ibrahim was born from his mother Azar wanted to take him to al-Namrud to kill him but his wife said: “Don’t take your son to the Namrud who will kill him”…(until the end of the narration).
Source: al-Kafi vol 8 pg 366.
al-Majlisi said: Hasan in al-Miraat 26/548.
Thus the Shia belief that the prophets and Imams all come from a pure Muslim bloodline is destroyed by the Sahih from their infallible.
As for Ahlul-Sunnah we follow the clear Quranic verse and the Sahih Ahadith in our books and we don’t care:
Narrated Abu Huraira: The Prophet said, “On the Day of Resurrection Abraham will meet his father Azar whose face will be dark and covered with dust.(The Prophet Abraham will say to him): ‘Didn’t I tell you not to disobey me?’ his father will reply: ‘Today I will not disobey you.’ ‘Abraham will say: ‘O Lord! You promised me not to disgrace me on the Day of Resurrection; and what will be more disgraceful to me than cursing and dishonoring my father?’ Then Allah will say (to him):’ ‘I have forbidden Paradise for the disbelievers.” Then he will be addressed, ‘O Abraham! Look! What is underneath your feet?’ He will look and there he will see a Dhabh (an animal,) blood-stained, which will be caught by the legs and thrown in the (Hell) Fire.”(Sahih al-Bukhari – Book #55, Hadith #569)