Is there some way I can help my sister make better choices?

My sister is 23 years old and lives with my parents. They completely support her financially and she does not work or go to school. However, she is completely able to do those things if she wanted to. She recently began a relationship with a guy who does not even believe in God. Her beliefs have slowly changed over the years and she doesn't have much faith in God these days. I pray about her all the time because I want her to make better choices in her life. She gets very angry when I talk to her about her choices and believes I am being critical. Is there anything else I can do to help her realize she is on the wrong path in life and help her get things straight? Is praying enough?