Why differentiate between Catholic and Christian? The only true Christians are Catholics.
St. Peter Julian Eymard – Bad Catholic vs Good Protestant
People often say, “It is better to be a good Protestant than a bad Catholic.” That is not true! That would mean that one could be saved without the true faith. No. A bad Catholic remains a child of the family, although a prodigal; and however great a sinner he may be, he still has a right to mercy. Through his faith, a bad Catholic is nearer to God than a Protestant, for he is a member of the household, whereas the heretic is not. And how hard it is to make him become one!
St. Peter Julian Eymard