John Gill Commentary 1 Timothy 6:4

"he is puffed up, knowing nothing, but doting about questionings and disputes of words, whereof cometh envy, strife, railings, evil surmisings," — 1 Timothy 6:4 (ASV)

He is proud
Or swelled and puffed up with a haughty air the faithful ministers of the word. The doctrines of grace are of an humbling nature, especially when they are spiritually and experimentally understood and received; but notional knowledge, knowledge of natural things, and the doctrines of men, such as are of their own invention, fill the mind with pride and vanity:

knowing nothing ;
as he ought to know; not anything that is solid and substantial; nothing of the Gospel of Jesus Christ: he may have knowledge of natural and civil things, but not of spiritual ones; he may have collected a medley of knowledge together, but what will be of no real use either to himself or others:

but doting about questions and strifes of words :
or he is "sick or diseased"; his mind is distempered; he is like one in a fever, that is delirious; his head is light and wild; his fancy is roving, and he talks of things he knows not what; his head runs upon "questions"; foolish and unlearned ones, about the law and works, and the necessity of them to justification and salvation; concerning genealogies, and other fruitless and unprofitable subjects:

and strifes of words ;
mere logomachies; contending and quarrelling more about words than things, which tend to no profit, but to the subverting and confounding of hearers. The ill effects of which are as follow:

from which comes envy :
at the superior gifts and talents of others; at their success, and any little degree of honour and respect they have from others; which shows that such men, in whom this vice is a governing one, are carnal men, for this is a work of the flesh; and that they are destitute of charity, or the grace of love, which envieth not: also from hence comes

strife ;
contention, quarrelling; the peace and comfort of particular persons, and even of whole communities, are broken and destroyed hereby; for foolish and unlearned questions gender strifes, (2 Timothy 2:24 2 Timothy 2:25) which are very unbecoming the servants of the Lord, and very uncomfortable to the churches of Christ: yea, these also produce

railings ;
at one another, and especially at the faithful ministers of the Gospel; for when the false teachers cannot overcome them by Scripture and argument, they fall to railing and reviling of them: or entertain

evil surmises ;
groundless suspicions: or from hence follow, as the words may be rendered, "wicked opinions": concerning the being, perfections, purposes, and providence of God; concerning the person and offices of Christ; concerning the law and Gospel, grace and good works; and so the Syriac version renders it, "an evil opinion of the mind".