Institutes of the Christian Religion, 3.19.7

7. The third part of this liberty is, that we are not bound before God to any observance of external things which are in themselves indifferent, (ἀδιάφορα,) but that we are now at full liberty either to use or omit them. The knowledge of this liberty is very necessary to us; where it is wanting our consciences will have no rest, there will be no end of superstition. In the present day many think us absurd in raising a question as to the free eating of flesh, the free use of dress and holidays, and similar frivolous trifles, as they think them; but they are of more importance than is commonly supposed. For when once the conscience is entangled in the net, it enters a long and inextricable labyrinth, from which it is afterwards most difficult to escape. When a man begins to doubt whether it is lawful for him to use linen for sheets, shirts, napkins, and handkerchiefs, he will not long be secure as to hemp, and will at last have doubts as to tow; for he will revolve in his mind whether he cannot sup without napkins, or dispense with handkerchiefs. Should he deem a daintier food unlawful, he will afterwards feel uneasy for using loaf-bread and common eatables, because he will think that his body might possibly be supported on a still meaner food. If he hesitates as to a more genial wine, he will scarcely drink the worst with a good conscience; at last he will not dare to touch water if more than usually sweet and pure. In fine, he will come to this, that he will deem it criminal to trample on a straw lying in his way.

For it is no trivial dispute that is here commenced, the point in debate being, whether the use of this thing or that is in accordance with the divine will, which ought to take precedence of all our acts and counsels. Here some must by despair be hurried into an abyss, while others, despising God and casting off his fear, will not be able to make a way for themselves without ruin. When men are involved in such doubts, whatever be the direction in which they turn, every thing they see must offend their conscience.

John Calvin and Henry Beveridge, Institutes of the Christian Religion, vol. 2 (Edinburgh: The Calvin Translation Society, 1845), 434–435.

It seems BPC is rejecting John Calvin teaching on wine!