Allah states that even if the people were commanded to commit what they were prohibited from doing, most of them would not submit to this command, for their wicked nature is such that they dispute orders. Allah has complete knowledge of what has not occured, and how it would be if and when it did occur. This is why Allah said,
(And if We had ordered them (saying), "Kill yourselves (i.e. the innnocent ones kill the guilty ones)) until the end of the Ayah. This is why Allah said,
وَلَوْ أَنَّهُمْ فَعَلُواْ مَا يُوعَظُونَ بِهِ
(but if they had done what they were told,) meaning, if they do what they were commanded and refrain from what they were prohibited,
1.Siddiq, lexically means 'very truthful'. In the Islamic terminology, it normally refers to those Companions of a prophet who excel all others in their submission to Allah and His Messenger. They enjoy the highest status of piety after the Prophets, like Sayyidna Abu Bakr ؓ
2. Shuhada (plural of Shahid) means the persons who sacrificed their lives in the way of Allah. The word has not been translated here by the word 'martyr` which sometimes is taken as an equivalent of Shahid, because the word 'martyr' is also applied for the persons killed in ethnic or racial wars while they may not be termed as 'Shuhada' in the Islamic terminology.
By pursuing a course of selfishness and opportunism in life, the individual incurs the greatest loss, i.e. he fails to find the straight path (as explicitly laid down in the Book of God and sayings of the Prophet) which could have led him to his Lord. One who does not think objectively, who is opportunistic in his thinking, will fail to find that straight path, no matter how clearly it may have been shown to him. This results from his viewing religion, not from a correct perspective, but from the standpoint of his own desires and convenience, so that an image of religion moulded by his own perceptions is formed in his mind. Though a claimant of faith, he remains deprived of it. How could such a person be eligible for Paradise, which is to be inhabited only by those who have embraced the Faith, rising above all considerations of self-interest and expediency, who have stood by the covenant of God, being witnesses for the truth to the ultimate extent, and having lead totally pious lives?
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.