The next verse reads وَكَذٰلِكَ جَعَلْنَا لِكُلِّ نَبِيٍّ عَدُوًّا مِّنَ الْمُجْرِمِيْنَ (In a similar way We made for every prophet an enemy from among the sinners - 25:31). It means that if your adversaries do not accept Qur'an, it is not something new. In the past as well people have defied Our message and the messengers had to contend with that. The best course for you also is to be contended.

Abandoning to follow Qur'an is a great sin

On the face of it abandonment of Qur'an means its denial or non non-acceptance, which is expected only from the infidels. However, in certain traditions it is reported that those Muslim who do believe in the Qur'an but neither they read it nor try to follow it fall as much within the ambit of this category of people. Sayyidna Anas ؓ has quoted the Holy Prophet ﷺ as saying:

من تعلّم القرآن و علّق مصحفہ لم یتعاھدہ ولم ینظر فیہ جاء یوم القیامۃ متعلقا بہ یقول : یا ربّ العالمین ان عبدک ھذا اتخزنی مھجوراً فاقض بینی و بینہ ۔ ذکرہ الثعلبی (قرطبی)

The person who has learnt Qur'an and then hanged it (on the wall), neither he recites it routinely nor ponders over its injunctions will be brought on the Doomsday with Qur'an hanging by his neck with a sling, and will complain before Allah Ta’ ala 'this servant of Yours had abandoned me, so decide between me and him". (Qurtubi)