No person can adjust and draw the line exactly for another. There are so many particulars in every situation, of which a stranger cannot be a competent judge, and the best human advice is mixed with such defects that it is not right to expect others to be absolutely guided by our rules; nor is it safe for us implicitly to adopt the decisions or practices of others.
But the Scripture undoubtedly furnishes sufficient and infallible rules for every person, for whatever the circumstances; and the throne of grace is appointed for us to wait upon the Lord for the best exposition of His precepts. Thus David often prays to be led in the right way, “Show me the path where I should walk, O Lord; point out the right road for me to follow. Lead me by Your truth and teach me.” Psalm 25:4-5
By frequent prayer, close acquaintance with the Scripture, and a habitual attention to the frame of our hearts, there is a certain delicacy of spiritual taste and discernment to be acquired, which renders a proper judgment concerning the nature and limits of questionable things. Love to Christ is the clearest and most persuasive factor; and when our love to Jesus is in lively exercise, and the rule of his Word is in our eye, we seldom make great mistakes!
The believer should also avoid whatever has a tendency to dampen and indispose his spiritual mindedness. For such things, if they are not condemned as downright sinful, if they are not absolutely unlawful; yes though they are, when duly regulated, lawful and right; yet if they have a repeated and evident tendency to deaden our hearts to Divine things, there must be something in them which is wrong to us! And let them promise what they will, they do but rob us of our gold to pay us with pebbles! For the light of God’s countenance, and an open cheerfulness of spirit in walking with Him in private is our chief joy, and we must be already greatly hurt if anything can be pursued, allowed, or rested in as a tolerable substitute for it.
– John Newton