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?
I’d say yes, as long as they’re tolerant of their children questioning those beliefs and developing their own later on in life. Parents will always make an impression on their kids, that’s just what being a parent is. It can get more nuanced of course. Teaching your kids homophobia is unethical, but that’s regardless of whether it’s for religious or other reasons.