Guidance from Allah (SwT) is integral to belief, while disbelievers remain devoid of guidance. In other words, you have to believe and guidance would come your way, so that you are not led astray, instead it ensures your stay on the path of righteousness, which leads to Garden of Bliss. In several verses that follow, the path of belief and agony of disbelief is laid down:
‘’Had the people of Scriptures believed and been righteous, We would have remitted their sins, and admitted them into the Garden of Bliss’’ (5:65)
The Holy Verse pertains to people of Scriptures—Ahl-ul-Kit’ab. The Scriptures were revealed to Ahl-ul-Kit’ab from earliest times. Many however committed evil, ignoring what was revealed, while a moderate community stuck to the path of belief and righteousness:
‘’Had they observed the Torah, and the Gospel, and what was revealed to them from their Lord, they would have consumed amply from above them, and from beneath their feet. Among them is moderate community, but evil is what many of them are doing’’ (5:66) It is laid down that had the people of Scriptures—the Jews, the Christians observed what was revealed to them in Torah and the Bible, they would have gained their spiritual sustenance from variety of sources, spread everywhere by nature.
However, majority of them stuck to evil, leaving a moderate community, who stuck to the path of belief and righteousness.
For the people of the Book-- Ahl-ul-Kit’ab, yet guidance came in what was revealed to Prophet of Islam (pbuh) in the book of ultimate guidance, the Muslims revere as Quran.
The Prophet (pbuh) is asked to deliver the message, in order to fulfil the assigned mission: ‘’O Messenger, convey what was revealed to you from your Lord.
But if you do not, then you would not have delivered His Message. And God will protect you from the people. God does not guide the disbelieving people.’’ (5:67)
In spite of the final message delivered in clear terms, if some remain mired in disbelief, Almighty Allah (SwT) is not going to provide them guidance.