"I am the true vine, and my Father is the husbandman. Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit. Now ye are clean through the word which I have spoken unto you. Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me." - John 15:1-4
Tell them in a curt few words that to believe in Christ and the creation story that goes with him is an evolutionary advantage. Therefore, if you believe in evolution and Darwinism you must also believe in the lack of evolution and Christ. If they're a logician you might just change their mind, assuming they accept your premise.
I love paradoxes that only I understand.