Authorized Version
    For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.

American Standard Version
    for he is a minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is a minister of God, an avenger for wrath to him that doeth evil.

The Bible in Basic English
    For he is the servant of God to you for good. But if you do evil, have fear; for the sword is not in his hand for nothing: he is God's servant, making God's punishment come on the evil-doer.

The Darby Bible
    for it is God's minister to thee for good. But if thou practisest evil, fear; for it bears not the sword in vain; for it is God's minister, an avenger for wrath to him that does evil.

The Webster Bible
    For he is the minister of God to thee for good. But if thou doest that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, an avenger to [execute] wrath upon him that doeth evil.

Young's Literal Translation
    for of God it is a ministrant to thee for good; and if that which is evil thou mayest do, be fearing, for not in vain doth it bear the sword; for of God it is a ministrant, an avenger for wrath to him who is doing that which is evil.

World English Bible
    for he is a servant of God to you for good. But if you do that which is evil, be afraid, for he doesn't bear the sword in vain; for he is a minister of God, an avenger for wrath to him who does evil.