That is such nonsense. Being raised in a religion has been shown to be abundantly helpful to a child. It helps in so many different ways. For example, teens are much less likely to commit suicide. Another example is that in religious groups, co-parenting, including by members who have no children, is much higher than in secular populations, which gives children a much more loving, stable, healthy upbringing than isolated parenting.
Suicide:
Parents' spirituality or religion tied to lower suicide risk in kids - Reuters
Judaism can protect against suicide: Israeli study
Better behaved and well adjusted. This may be directly due to the pro-family, pro-parenting support system in the community described below.
Study: Religion is Good for Kids
Better parenting support: in religious communities, extended families reach out to support young parents in both practical ways and with advice, especially unmarried members. This also extends to members of the faith community who are not relatives.
I couldn't find the link, but I read this about three weeks ago.