This sounds like solid parenting; my only concern is that you might not be taking the psychology of children into account. Children sometimes really do need an authority figure to tell them what's true and what isn't; the reason for truth is far less important at that stage (and can be given later, maybe even years later).

One issue that could arise is that if you don't show authority then your child may instead gravitate to other authority figures and believe them instead. A child may paradoxically put more faith in the opinions of someone who insists on them irrationally than someone who is willing to change their beliefs according to reason or evidence (actually, this applies to many adults too). It's possible that "demeanor and tone of voice" trumps "this person was wrong in the past."

The point is that children's reasoning is far far less developed than adults and you have to take their irrationalities into account when teaching them.