I think most people who call themselves relativists are not, in practice.
Sinners think they are saints, but saints know they are sinners.
Sin comes from not realizing God's love. Sin comes from thinking ourselves only as sinners, while overcoming sin comes from thinking ourselves as overcomers. We act our our perceived identities.
It was a very stupid mistake to think you could deal with heresy by burning heretics. It's the very same mistake that modernist Catholics are making today in reverse. They think you can love heretics by loving heresies.