God has created human beings to be able to achieve some pretty amazing things. In and of ourselves, there are actually many things we are able to do simply due to the gifts that God has deposited in us. The Bible is clear that the gifts of God are without repentance; therefore, the ability that lies in our natural gifts will continue to operate regardless of whether we are living for Christ or not.
For God’s gifts and his call can never be withdrawn. (Romans 11:29, NLT)
Here's the thing though... when God calls us to do something, it usually requires more than the ability we currently posses. Think about all the people in the Bible that God used, how many of them would've been able to achieve what they did without God? If Moses had placed his rod in the Red Sea without the supernatural power of God, would the sea still have parted? Or if Joshua and the children of Israel had walked around the city of Jericho without the supernatural power of God, would the walls still have fallen down?
Granted, God does use our natural gifts to accomplish His will; however, our natural gifts alone are not enough. If we really want to sow into eternity and to accomplish the supernatural, then we are going to require some "super" to be added to our natural.
Now all glory to God, who is able, through his mighty power at work within us, to accomplish infinitely more than we might ask or think. (Ephesians 3:20, NLT)