You're right. There are many assumptions involved on the evolutionist's part. The real issue are the pre-believes one takes to the evidence. If one holds to a naturalistic worldview, that the whole universe is a closed system and nothing intervenes from the outside, what else can be the necessary conclusion than the theory of evolution?
Great response! Thanks a lot!
That's a simple truth Robert Morey from "Faith Defenders" uses to point out: Your starting point will determine where you will end. If you start with man (instead of God and his word) you will end by man. Also, if you start with an naturalistic framework you will come to naturalistic conclusions. The means will determine the ends. If one starts with God, he will end by God. There is no neutrality possible rather an unavoidable antithesis where friendship with that (system of the) world equals to enmity with God.