Math test simple

\[\newcommand{\LetThereBe}[2]{\newcommand{#1}{#2}} \newcommand{\letThereBe}[3]{\newcommand{#1}[#2]{#3}}\]\[\letThereBe{\addTag}{2}{\cssId{#1-#2}{\tag{#2}}} \letThereBe{\refTag}{2}{\href{###1-#2}{(\text{#2})}}\]\[\letThereBe{\eqT}{1}{\addTag{eq}{#1}}\letThereBe{\secT}{1}{\addTag{sec}{#1}}\]\[\letThereBe{\eqRef}{1}{\refTag{eq}{#1}} \letThereBe{\secRef}{1}{\refTag{sec}{#1}}\]\[\LetThereBe{\foo}{\mathrm{foo}}\]

This does not render, \(\foo\)!