Yes, they certainly could change, through God’s intervention; it happens all the time. I think, for example, of the countless people who grew up as convinced atheists in Communist Eastern Europe and the old Soviet Union, but are now sincere believers in God and are committed followers of Jesus Christ.
Admittedly many atheists today do all they can to erect barriers in their hearts and minds against God. Some even want to drive out any mention of God from our public life. And no matter how much you argue with them or try to reason with them, their minds are seemingly closed. The reason, I’ve found, is because they want to run their own lives, instead of humbly submitting to God.
But God made us for Himself, and when we leave Him out of our lives an empty place is left in our hearts, and ultimately our lives are meaningless and without hope. Only God can fill that empty place and give us hope for the future—as former atheists today are discovering. Job said, “For what hope have the godless when they are cut off?” (Job 27:8).
Pray for your friends who claim to be atheists and don’t want anything to do with God. Remember: God can do what we never can do—including changing someone’s heart and mind. In addition, make sure of your own commitment to Jesus Christ, and then ask Him to help you be an example of Christ’s love and purity to your friends.