I. A lawful oath is part of religious worship, wherein, upon just occasion, the person swearing solemnly calls God to witness what he asserts, or promises, and to judge him according to the truth or falsehood of what he swears.
II. The name of God only is that by which men ought to swear, and therein it is to be used with all holy fear and reverence. Therefore, to swear vainly, or rashly, by that glorious and dreadful Name; or, to swear at all by any other thing, is sinful, and to be abhorred. Yet, as in matters of weight and moment, an oath is warranted by the Word of God, under the New Testament as well as under the old; so a lawful oath, being imposed by lawful authority, in such matters, ought to be taken.
III. Whosoever takes an oath ought duly to consider the weightiness of so solemn an act, and therein to avouch nothing but what he is fully persuaded is the truth: neither may any man bind himself by oath to any thing but what is good and just, and what he believes so to be, and what he is able and resolved to perform. Yet it is a sin to refuse an oath touching any thing that is good and just, being imposed by lawful authority.
IV. An oath is to be taken in the plain and common sense of the words, without equivocation, or mental reservation. It cannot oblige to sin; but in any thing not sinful, being taken, it binds to performance, although to a man’s own hurt. Not is it to be violated, although made to heretics, or infidels.
V. A vow is of the like nature with a promissory oath, and ought to be made with the like religious care, and to be performed with the like faithfulness.
VI. It is not to be made to any creature, but to God alone: and that it may be accepted, it is to be made voluntarily, out of faith, and conscience of duty, in way of thankfulness for mercy received, or for the obtaining of what we want, whereby we more strictly bind ourselves to necessary duties: or, to other things, so far and so long as they may fitly conduce thereunto.
VII. No man may vow to do any thing forbidden in the Word of God, or what would hinder any duty therein commanded, or which is not in his own power, and for the performance whereof he has no promise of ability from God. In which respects, popish monastical vows of perpetual single life, professed poverty, and regular obedience, are so far from being degrees of higher perfection, that they are superstitious and sinful snares, in which no Christian may entangle himself.