Albert Barnes on 2 Timothy 2:23

But foolish and unlearned questions avoid. 1Timm 1:4; 1Timm 1:6; 1Timm 4:7. The word unlearned, here, means trifling; that which does not tend to edification; stupid. The Greeks and the Hebrews were greatly given to controversies of various kinds; and many of the questions discussed pertained to points which could not be settled, or which, if settled, were of no importance. Such has been the character of no small part of the disputes which have agitated the world. Paul correctly says that the only effect of such disputes is to engender harsh contention. Points of real importance can be discussed with no injury to the temper; but men cannot safely dispute about trifles.

(g) "questions" 2Ti 2:16