From the pen of J.C. Ryle,

First of all speaking of the strong words Christ had concerning the Pharisees, Scribe etc.

What may we learn from these tremendously strong expressions? How is it that our gracious and merciful Saviour used such cutting words about people who at any rate were more moral and decent that the publicans and harlots? It is meant to teach us the exceeding abominableness of false profession and mere outward religion in God’s sight. Open profligacy and wilfil obedience to fleshly lusts are no doubt ruinous sins, if not given up. But there seems nothing which is so displeasing to Christ as hypocrisy and unreality.

Secondly his exhortation to us,

Let there be nothing of reserve, or double-dealing, or part-acting, of dishonesty, of sham, of counterfeit in your Christianity. Never be content to wear a cloak of religion. Be all that you profess. Though you may err, be real. Though you may stumble, be true.