Do they believe? Certainly if they do not believe in the gospel at an age when they are undoubtedly old enough to know what it is and reject it, they shouldn't be baptized. If they do believe, what's the problem?
"I wish it were in my power, after this day, to cry down all love but the love of Christ, and to cry down all gods but Christ, all saviours but Christ, all well-beloveds but Christ, and all soul-suitors and love-beggars but Christ." -Samuel Rutherford, Letter CCIII. to William Gordon at Kenmure