"The LORD is a jealous God, filled with vengeance and wrath." (Nahum 1)
"I have wiped out many nations, devastating their fortress walls and towers. Their cities are now deserted; their streets are in silent ruin. There are no survivors to even tell what happened. I thought, 'Surely they will have reverence for me now! Surely they will listen to my warnings, so I won't need to strike again.' But no; however much I punish them, they continue their evil practices from dawn till dusk and dusk till dawn." (Zephaniah 3:6)
The wrath of God used to be one feared by Christians. They were kept prude and solemn as they tended to their Christian duties, knowing that they served a God who was capable of delivering great pain and suffering.
As society advanced and man discovered they had a greater control over their comfort than they had previously imagined, the interpretation of the Bible shifted. The focus shifted to the indication that God loved his creations and wanted to shower them with blessings (that last part was sort of added by his creations).
The Bible reflects both realities...as you would expect any Divine Being, being all-powerful and capable of - well - anything...that includes great joy and great pain. The Bible suggests their God delivers both.
But Earth has become a very fun place to be. Running hot water, chocolate, cotton candy, feather comforters, modern medicine, pornography, carnivals, fast cars, planes, TV, movies, toilets that FLUSH, computers, the Internet, and yachts! It's playground out there compared to the days when the Bible was first penned, to the first devoted followers of the Bible -- who likely witnessed more "wrath" than "blessings".
So...it's not hard to understand why people of the Dark Ages, crapping in their chamber pots, watching their babies die of starvation read the Bible and said "WRATH!" and the people sitting in their air-conditioned mansions eating Chinese take-out today read it and say "BLESSINGS!".
The reasons and the interpretations and the reasons for the interpretations all make sense to me. But...what if the people from the Dark Ages were right and the people today are wrong? What if God is a vengeful, mean prick that we should fear?