You say: "Oh people of the Book! You are not upon anything until you keep up Thorah and Gospel, and whatever has been sent down into you from your Lord. Surely what has been sent down into you from your Lord will increase for most among them arrogance and disbelief, then you don’t despair upon the disbelieving people".
The verse commands the Messenger to say to the Jews and Christians of that time that they are good for nothing until they follow and testify Lord’s Book Adhikr which testifies and safeguards all the 312 previous Books and their upright Explanations as explained in verse 5: 48. But the 999 out of every thousand becomes Fujjar who will be entrapped by Satan as explained in verse 4: 118. "You don’t despair upon the disbelieving people" told in verse means that the Messenger or believer is not sent as a custodian upon anyone.
Today these verses are read by the Fujjar. They neither follow nor testify Adhikr and so they are the worthless people as told in verse 25: 18. They all are carrying the Body of Lord’s Book like burden carrying donkeys as told in verse 62: 5. The similitude of these aimless and heedless people is that of a dog that never changes its attitude whether disturbed or not as explained in verses 7: 175-176.
They have to bear the burden of all destructive and mischievous activities that are happening anywhere in the world since they are rejecting Adhikr which is the Balance and Trust to keep the universe in its equilibrium. They will perish their life witnessing against their soul that indeed they were disbelievers as told in verses 7: 37 and 39: 59. Adhikr will increase nothing but filth over filth for these Mujirims as explained in verse 2: 14. Each group among the Fujjar are destined into the seven doors of Hell as explained in verse 15: 44. See explanation 2: 6-7, 159-161; 3: 72-73; 4: 63 and 174-175.