I found John Calvin’s comments on 1 Timothy 4:1-3 interesting. The passage in question reads: “Now the Spirit expressly says that in later times some will depart from the faith by devoting themselves to deceitful spirits and teachings of demons, through the insincerity of liars whose consciences are seared, who forbid marriage and require abstinence from foods that God created to be received with thanksgiving by those who believe and know the truth” (ESV).
For how can faith be completely overturned by a prohibition of certain foods or of marriage? But we must take a wider consideration into account, that here men are inventing a perverted worship of God at their own pleasure, and by daring to forbid the use of good things God has permitted, are claiming to be masters of their own consciences. And as soon as purity of worship is perverted nothing remains whole or healthy any longer and faith is completely destroyed. Thus, although the Papists laugh at our criticisms of their tyrannical laws about external observances, we know that we are dealing with a most serious and important matter, for, as soon as the worship of God is infected with such corruptions, the doctrine of faith is destroyed. The controversy is not about flesh or fish, or about black or ashen colours, or about Wednesday or Friday, but about the mad superstitions of men who wish to obtain God’s favour by such trifles and by contriving a carnal worship, invent for themselves an idol in God’s place. Who would deny that this is apostasy from the faith?*
*The Second Epistle of Paul the Apostle to the Corinthians and the Epistles to Timothy, Titus and Philemon (T. A. Smail, trans.; Grand Rapids: Eerdmans: 1964), 237.