Sound advice. Ya know my parents cautioned me not to marry a girl who wasn’t a Christian. I learned the hard way parents know best.
However, it's as easy to lie about being a Christian as it is to lie at the border and say, "I don't have Ebola symptoms."
We have seven children---three now married.
We did not admonish our children and then release them to date whomsoever they wanted.
We trained our children to watch the behavior and interests of potential mates prior to expressing interest, and to investigate the propensities of potential mates by speaking to pastors and others involved in their lives.
Is the 'potential' known to have been openly practicing Biblical Christianity in and through their local church prior to knowing that my children even exist?
So, the admonition is "Only consider an individual whose life had already been openly and certifiably demonstrating their faith in Christ prior to meeting you."
Obviously, to do that, it requires exposure to 'potentials' within a limited range of churches and multi-church activities, where high standards of courtship, marriage, and childhood/teen discipline already exist across the church or fellowship of churches.