Couple of reasons. First of all, because Darwinian Evolution is atheistic to the core, it is the faith of those whom we wish to reach who don't believe in God. How can you tell someone "Heaven is a free gift" when they don't believe in God or heaven? So we study the belief system of those to whom we would like to speak of Jesus to. But before we speak of Jesus, we have to tell the story of creation. Part of that story telling is knowing how to give a defense of the reasons why belief in God is necessary to satisfactorily explain the universe and life.
Hebrews 11:6 tells us that before one can come to God, he must believe that He is and that He is a rewarder of those who diligently seek Him. So belief in the necessity of God is a starting point for evangelizing an atheist.
Consider Peter, when he was preaching to the Jews, how he began his sermon by quoting scripture from the prophet Joel and then said:
“Men of Israel, hear these words: Jesus of Nazareth, a Man attested by God to you by miracles, wonders, and signs which God did through Him in your midst, as you yourselves also know—Him, being delivered by the determined purpose and foreknowledge of God, you have taken by lawless hands, have crucified, and put to death.
So for those who already believe in God, they can be taken directly to the Bible and immediately be told about Jesus. There was no need for an apologetic about Creation, they already believed that.
Now consider the apostle Paul when he spoke to the Greeks at Mars Hill. Before he speaks of Jesus and of sin and of salvation, he starts with an apologetic about the true creator God.
"God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands. Nor is He worshiped with men’s hands, as though He needed anything, since He gives to all life, breath, and all things."
There is a second reason to study Creation Science--that is to build up our own faith. Yes, I know you believe but none of us are immune to the fiery darts of the wicked one. We must defend against them with the shield of faith. You can strengthen that shield by learning good reasons why what is being taught in our schools about science should not cause us to doubt. And it is not a blind faith we have. Rather it is based on good science starting from a different perspective.
Our children are being challenged every day by teachers and professors who do not believe in God and have the support of the scientific establishment for such a belief. They offer up scientific dogma which seems to go against a belief in the necessity of Creation. It is hard to withstand this bombardment without hearing from other, God honoring, Bible believing scientists who see through the logic and arguments and are able to interpret the facts in a way that will build up our faith and give us confidence that the Bible is supported by what we observe in the real world.
You may not understand everything these respected scientists who believe in creation are saying but even so, it is good to know someone who is smarter than me has thoroughly investigated the science and has concluded that the Bible is true based upon his own research. God is not afraid of our questions, in fact he commanded us to "subdue the earth" and that's what we are going to do in this course.