Well do you want to use the Hebrew words of "faithful" and "holy" for earthly believers? Dictionary.com defines "saint" as a person of great holiness, virtue, or benevolence. The Psalms call believers "holy". Sounds like the same thing to me. The "faulty" interpretation is a stretch IMHO.
How would YOU define these Hebrew terms and does it make any difference?
HD, Christianity distinguished from the beginning that some people were "holier" than others. Those who distinguished themselves in their faith, and achieved what we Orthodox call "theosis" (santification) during their life time, were posthumously declared to be Saints, as we believe they are in heaven.
Obviously, not all believers are "saints" simply because they are believers. That is something +Paul invented, and something the Church never accepted. Being a Saint is a distinction among believers, not a common trait.
Some people attain holiness, others don't. That much is clear.