I love Dainel Plainview as I pity his spiritual stuggle and descent into darkness which is the self defeat possible for anyone and a warning to viewers. Also, he does love his son and has a moral compass even if he makes mistakes and commits various evil acts.

Daniel Plainview is much more than just evil though, he represents the dark potential of humanity. Oil in the movie I take to be a symbol of the darkness inherint to the soul of every human being. Throughout the movie, until the end, Daniel is always searching and mining. By the end of the film all the oil, blood and darkness have been dug up to come critical spiritual breaking point and both Eli and Daniel die spiritually (Daniel kills himself spitiually- "I'm finished"). In Genesis it is said that -"The wages of sin is death" (for everyone of course, not just Daniel and Eli)

If the Earth (a symbol of the world) is a great body, we can think of Oil as its dark blood. There Will Be Oil and so also, There will be Blood. Most striking are the shots of pools of oil on the ground, which indiciate darkness that has come to the surface (notice the large pool of oil just before Daniel beats Eli into the mud).

Taken together with Eli, Daniel is a warning of avoiding the truth that God is Love or at least, not money and pride. Vanity, greed and materialism should not take center stage in a persons spiritual life. Superficial religion and the worship of mammon are dangers that America, humanity and we each as individuals all face. Mary and H.W by the end of the film appear to be religious people involved in business and we don't expect a tragic future for them. So relgion and capitalism in themselves are not bad things, only the oil/blood/darkness of every human being and the world.

This movie asks each of us- Dig up and live out the darkness and where will it take you?

Daniel made some bad choices.  He had his chances but was lost. 

"Do you reject the blood?  Or do you embrace the blood?"

Depends on which blood you're talking about: the blood of the Lamb or the blood of the Earth?  The preacher and the oilman may embrace different kinds of blood, but maybe it doesn't matter, as they both are misguided in their obsessions.

If anyone needs any more convincing that the genie isn't going back into the bottle any time soon, rent "Who Killed the Electric Car?"

First, I'd like to say that I agree with those that believe that Daneil is evil.

Second, I think you all take it way too far if you ask me. 

I think there are much less figurative scriptings and hidden meanings in this screen play than has been discussed in these forums. I do, however, believe it is good to discuss this sort of thing at great lengths as well. Speaking of mans struggle to survive and the similarity between blood and oil and so on and so forth is good because it challenges us to look within to find meaning in our own lives by casting the reflections of others life works accross our own. As I said before, this work is much more litteral than you have been lead to believe. It's all laid out nicely for you if you watch and listen properly. There is proof of this in that Daniel doesn't lie once throughout the whole movie, though some of his words are very mis-leading to the other characters, they have also mis-lead the viewers. To lie is to say something un-truthful, and un-truthfulness comes from saying words you do not believe. Now, that being said, if you watch the movie over, you can actually see the evil in his eyes when he is digging his first well and finds the precious metal. You can see the evil in his eyes when he speaks to the town folks about bread pouring out their ears and you can see the evil in his eyes when he calmly states "I'll give them quail prices". He does everything that he says he's going to do, there are no supprises and the reason, I believe, that so many people debate his morality is that most of us like him and, being good people, we make excuses for him and hope for the best from him.

That's all I have, I'm finished. 

veni vidi vici - I came, I saw, I conquered

and

quod me nutrit destruit - What nourishes me destroys me

he was driven by his own succes in business so much so that it lead to his demise in life

The director who made "Downfall" also made the new remake of the "Invasion of Body Snatchers", in which the moral of the story is that the essence of humanity is war and conflict. For Upton Sinclair, it was the principle of competition that was the root of wars and exploitation. For PTA, the principle of competition can be found in the sibling rivalry of Cain and Abel (as in Steinbeck's "East of Eden"). In the bowling alley finale, Daniel wakes up only after Eli says: "Daniel, my brother!". When Daniel kills Eli, we can think of Eli as Abel. But, then we have to remember the scene in which Eli attacks his father (Abel) for selling the land so cheaply to Daniel. So, both Daniel and Eli are Cains. They are both evil, they are both monsters, and still, they are unmistakably human, like Hitler.