Upholder
/ʌpˈhəʊldər/
Definition 1 of 2
Pro Tip 1/3Positive Connotation
Using 'upholder' positively shows strong support or advocacy for a cause or belief. 
She was known as the upholder of human rights.
Pro Tip 2/3Moral Implication
'Upholder' often implies a moral stance or commitment to ethical principles. 
He became an upholder of the community’s unwritten ethical code.
Pro Tip 3/3Serious Tone
'Upholder' is used seriously and respectfully, fitting more formal contexts. 
The judge is an upholder of the law, ensuring justice prevails.