The context of 2:170 I quoted is about declaring things lawful or unlawful when this is declared in the Quran. They do not want to follow Quran because it goes against what their ancestors have taught them. If you want full context, here is the only Guidance we require to Guide us, unless you have 'ancestor or revelation other than Quran' disease in the heart:
2.2. This is the Book; in it is guidance sure, without doubt, to those who fear Allah.
2.3. Who believe in the Unseen, are steadfast in prayer, and spend out of what We have provided for them;
2.4. And who believe in the Revelation sent to thee, and sent before thy time, and (in their hearts) have the assurance of the Hereafter.
2.5. They are on (true) guidance, from their Lord, and it is these who will prosper.
2.6. As to those who reject Faith, it is the same to them whether thou warn them or do not warn them; they will not believe.
2.7. Allah hath set a seal on their hearts and on their hearing, and on their eyes is a veil; great is the penalty they (incur).
2.8. Of the people there are some who say: "We believe in Allah and the Last Day;" but they do not (really) believe.
2.9. Fain would they deceive Allah and those who believe, but they only deceive themselves, and realise (it) not!
2.10. In their hearts is a disease; and Allah has increased their disease: And grievous is the penalty they (incur), because they are false (to themselves).
2.11. When it is said to them: "Make not mischief on the earth," they say: "Why, we only Want to make peace!"
2.12. Of a surety, they are the ones who make mischief, but they realise (it) not.
2.13. When it is said to them: "Believe as the others believe:" They say: "Shall we believe as the fools believe?" Nay, of a surety they are the fools, but they do not know.
2.14. When they meet those who believe, they say: "We believe;" but when they are alone with their evil ones, they say: "We are really with you: We (were) only jesting."
2.15. Allah will throw back their mockery on them, and give them rope in their trespasses; so they will wander like blind ones (To and fro).
2.16. These are they who have bartered Guidance for error: But their traffic is profitless, and they have lost true direction,