You just gotta look at it logically.
The Bible is "metaphor" or "allegory," or "old covenant" when it directs stuff that is popularly accepted now, and the "living word of God" when it tells you to do stuff that its followers find yucky.
EDIT: James and Edward, have a go at these:
"Thy bond-men and thy bond-maids which thou shalt have, shall be of the heathen that are round about you: of them shall ye buy bond-men and bond-maids. Moreover, of the children of the strangers that do sojourn among you, of them shall ye buy, and of their families that are with you, which they begat in your land. And they shall be your possession. And ye shall take them as an inheritance for your children after you, to inherit them for a possession, they shall be your bond-man forever."
"When a man strikes his slave, male or female, with a rod and the slave dies under his hand, he shall be punished. But if the slave survives a day or two, he is not to be punished; for the slave is his money."
—Exodus 21:20-21 (RSV)
"The lord of that servant will come in a day when he looketh not for him, and at an hour when he is not aware, and will cut him in sunder, and will appoint him his portion with the unbelievers. And that servant, which knew his lord's will, and prepared not himself, neither did according to his will, shall be beaten with many stripes."
"Let as many servants as are under the yoke count their masters worthy of all honor, that the name of God and his doctrine be not blasphemed. And they that have believing masters, let them not despise them, because they are brethren; but rather do them service, because they are faithful and beloved, partakers of the benefit."
—1 Timothy 6:1-2
(...implicitly condoning the practice)
You can't be the gay, but don't kill any back-talking kids any more.
You can marry one woman, but not many. You can divorce her, but you can't.
It all makes sense if you just read the (revised and translated multiple times) true Word of God.