Thank you for confirming the point that tattooing children is wrong, and you made the equivalence with circumcision so that is wrong too.
There are many things you can't do to your child, and many things you have to. As you say, you have to be convinced that these things are in the child's best interests. You can't beat your child, and you have to feed and educate him/her properly etc, etc.
Altering your child's body may be necessary in the event of illness etc, but not for any other reason, as you've confirmed. Circumcision comes into the category of things that are unnecessary.
There are many things you can't do to your child, and many things you have to. As you say, you have to be convinced that these things are in the child's best interests. You can't beat your child, and you have to feed and educate him/her properly etc, etc.
Altering your child's body may be necessary in the event of illness etc, but not for any other reason, as you've confirmed. Circumcision comes into the category of things that are unnecessary.