For many religious people, raising their children in their faith is an important part of their religious practice. They might see getting their kids into heaven as one of the most important things they can do as parent. And certainly, adults should have the right to practice their religion freely, but children are impressionable and unlikely to realize that they are being indoctrinated into one religion out of the thousands that humans practice.
And many faith traditions have beliefs that are at odds with science or support bigoted worldviews. For example, a queer person being raised in the Catholic Church would be taught that they are inherently disordered and would likely be discouraged from being involved in LGBTQ support groups.
Where do you think the line is between practicing your own religion faithfully and unethically forcing your beliefs on someone else?
Ideally when properly understood each religion usually means well and enhances oneself in some way, from my little studying into a couple popular ones they seem to be aiming for similar things so I’m less and less convinced of inherently biased religious practices and more and more convinced of sucky people.
I think spirituality goes hand in hand with mental health and when we understand it badly we dig ourselves into deeper holes or when we understand it rightly we keep ourselves from falling in holes.
If what you teach someone helps them, that is good, otherwise just leave them alone.