Change Color of Font Once They Have Been Defined

I have defined the color of my fonts in the preamble. What I am trying to accomplish is to change the color of just one word within the document, but I am unable to do this.

Usually, within the body of the document I would use:

\begin{document}

{\color{blue} This sentence is blue}

\end{document}


But for some reason this method does not work. Any thoughts would be much appreciated.

Here is my preamble:

\documentclass[letterpaper,10pt]{article}
\usepackage{latexsym}
\usepackage[empty]{fullpage}
\usepackage{titlesec}
\usepackage{marvosym}
\usepackage[usenames,dvipsnames]{color}
\usepackage{verbatim}
\usepackage{enumitem}
\usepackage[pdftex]{hyperref}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyfoot{}
\renewcommand{\footrulewidth}{0pt}

\urlstyle{same}

\raggedbottom
\raggedright
\setlength{\tabcolsep}{0in}

% Color definitions
\usepackage[usenames,dvipsnames]{xcolor}
\definecolor{date}{HTML}{666666}
\definecolor{primary}{HTML}{2b2b2b}

% Set main fonts
\usepackage{fontspec}
\setmainfont[Color=primary, Path = fonts/lato/,BoldItalicFont=Lato-RegIta,BoldFont=Lato-Reg,ItalicFont=Lato-LigIta]{Lato-Lig}
\setsansfont[Scale=MatchLowercase,Mapping=tex-text, Path = fonts/raleway/]{Raleway-ExtraLight}


You can use \addfontfeature to change the font color:

\documentclass{article}

\usepackage[usenames,dvipsnames]{xcolor}
\definecolor{primary}{HTML}{2b2b2b}

\usepackage{fontspec}
\setmainfont[Color=primary]{Latin Modern Roman}

\begin{document}

This sentance is in primary color.
This sentance is in primary color.

\end{document}


Result:

The Answer by Ralf works with XeLaTeX alternatively using LuaLaTeX you can continue using \color{blue}

Preamble

\usepackage{luacolor}

\begin{document}
This sentence is primary color
{\color{blue} This sentence is blue}
\end{document}