This just a quick in-depth analysis as to why evolutionary theory can be justified as scriptural from the perspective of scripture:
1) Humans are animals:
Eccl. 3:18 :
"I said in my heart concerning the state of the sons of men, that God might manifest them, and that they might see that they themselves are beasts."
2) Natural selection spoken of by Jesus - as a type of earthly creation: The parable of the sower which Jesus shows as God using natural selection as his means to create his spiritual kingdom (Matt. 13):
"Behold, a sower went out to sow. And as he sowed, some seed fell by the wayside; and the birds came and devoured them. Some fell on stony places, where they did not have much earth; and they immediately sprang up because they had no depth of earth. But when the sun was up they were scorched, and because they had no root they withered away. And some fell among thorns, and the thorns sprang up and choked them. But others fell on good ground and yielded a crop: some a hundredfold, some sixty, some thirty. He who has ears to hear, let him hear!" (Matt.13:3-9)
And, as we learn from throughout the NT, the second is a type of the first:
"Such as is the earthly, such also are the earthly: and such as is the heavenly, such also are they that are heavenly." (I Cor. 15:48 )
* what applies from earthly to heavenly, conversely applies from the heavenly creation (i.e., parable of the sower) to the earthly creation.
"These were a shadow of things that were soon to come, but the substance belongs to Christ." (Col. 2:17)
* the earthly things are shadows of heavenly things (i.e., similar in structure), so conversely, the creation of heaven using natural selection would imply that the earthly creation is also a shadow of the natural selection used by God to spread his spiritual word.
"and serve a copy and type of the heavenly things" (Heb. 8:5)
* the earthly things are a type of the heavenly things, so natural selection being used by God is a very powerful example that God would stay consistent and use it for earthly creation.
"But in accordance with His promise we are expecting new heavens and a new earth" (I Peter 3:13)
* just further evidence that the kingdom of God is a type of the physical universe now
"And I saw a new heaven and a new earth" (Rev. 21:1)
* More evidence to show that natural selection was a shadow of the things to come
3) Speaking of a new heavens and a new earth...:
This is a belief that Isaiah wrote about:
"For see, I am making a new heaven and a new earth: and the past things will be gone completely out of mind" Isa. 65:17
* Note: this scripture is very significant because it is comparing the current universe with the new universe, and it is using the same Hebrew word for 'making' as used in Gen. 1:1 when it said that God created the heavens and the earth. In other words, the 'new' is a type of the 'old', and just like the 'new' is taking time to create, it is also apparent that the 'old' took time.
Just to be clear that the new heavens and new earth is an evolutionary concept:
"Therefore be patient, brethren, until the coming of the Lord. See how the farmer waits for the precious fruit of the earth, waiting patiently for it until it receives the early and latter rain." (Jas. 5:7)
Notice that the new heavens and new earth is like a harvest. It takes time for the spiritual life to be produced. This is evolutionary since it 'new life' is being transformed from the 'old' species to an entirely 'new' species or 'new' creation:
"Therefore, if any man is in Christ, he is a new creature: old things have passed away; behold, all things have become new." (I Cor 5:17)
* Just the very act of converting is a speciation event - literally an act of creation in the Greek (Ktisis). When you compare this scripture with the farmer waiting for life to emerge, then you have new creatures being created throughout until, as Isaiah says, God has finished creating his new heavens and new earth.
Now, it is a big mistake to think God is so inconsistent as to so blatantly say that he's using evolutionary processes in the new creation and wouldn't use them in the old.
4) Direct words saying evolution in Genesis:
"Then God said, "Let the earth bring forth grass, the herb that yields seed, and the fruit tree that yields fruit according to its kind, whose seed is in itself, on the earth"; and it was so. And the earth brought forth grass, the herb that yields seed according to its kind, and the tree that yields fruit, whose seed is in itself according to its kind." (Gen. 1:11-12)
"Then God said, "Let the earth bring forth the living creature according to its kind: cattle and creeping thing and beast of the earth, each according to its kind"; and it was so." (Gen.1:24)
"This is the evolutionary history of the heavens and the earth when they were created, in the day that the LORD God made the earth and the heavens" (Gen. 2:4)
* There is no other explanation for the Hebrew 'toledoth'. It is only used to describe human generations which have sex and multiple (earth and the heavens can only have generations in the case of evolution). Hence, the translation above is valid.
Another interesting point is that this scripture is either part of the summary of Gen.1, or it is an introduction to the story of Gen.2. In other words, if you believe in the inspiration of scripture, then this is very inspiring to those who would like God's input to evolutionary theory. It shows that God could be talking about either chapter of creation, which means, that we can safely say that it is talking about both (i.e., if you can't distinguish then you must pick both). Hence, evolution is thoroughly part of the Genesis creation account (chapter 1 and chapter 2/3).
Anyway you slice it, there's just no biblical reason to be a special creationist. Why are people special creationists? Well, there's a lot of money to be made publishing books. So, careers are at stake. That explains a lot.