Cross out words with TikZ: line opacity

It is enough to draw the cross in a single path instead of two:

\draw[red,draw opacity=0.5, line width=1.5pt] (A.north west) -- (A.south east) (A.south west) -- (A.north east);

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{xcolor}
\usepackage{tikz}

\newcommand{\mycrossed}[1]{%
    \tikz[remember picture, baseline=(A.base)]{
        \node[inner sep=0pt](A){#1};
    }%
    \tikz[overlay, remember picture]{
        \draw[red,draw opacity=0.5, line width=1.5pt] (A.north west) -- (A.south east) (A.south west) -- (A.north east);
    }%
}

\begin{document}

Antonio Vivaldi was \mycrossed{an Italian} a Venitian Baroque musical composer, virtuoso violinist, teacher, and priest.

\end{document}

You can use the cross out shape node like that:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{xcolor}
\usepackage{tikz}
\usetikzlibrary{shapes.misc}

\newcommand{\txtcross}[1]{%
    \tikz[remember picture, baseline=(A.base)]{
        \node[cross out, 
            draw= red,
            line width=1.5pt,
            draw opacity=0.5,
            inner sep=0pt](A){#1};
    }
}

\begin{document}

Jean-Baptiste Lully  was \txtcross{a French} an Italian-born French composer, instrumentalist, and dancer

\end{document}

Based on @Hafid Boukhoulda answer, with some simplification (without remember picture option, slightly different node style definition):

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.misc}

\newcommand\mycrossed[1]{\tikz[baseline=(A.base)]
    \node[cross out, draw= red, draw opacity=0.5, line width=1.5pt,
          inner sep=0pt, outer sep=0pt] (A) {#1};%
                        }

\begin{document}
Antonio Vivaldi was \mycrossed{an Italian} a Venitian Baroque musical composer, virtuoso violinist, teacher, and priest. Antonio Vivaldi was \mycrossed{an Italian} a Venitian Baroque musical composer, virtuoso violinist, teacher, and priest.
\end{document}