A pastor told the following:
A member of his church approached Rev Spurgeon at the pulpit after a sermon at the Tabernacle, interrupting a discussion between the pastor and another person.
He announced that he was very grateful for the sermon delivered every Sunday and, after several months, was now a completely different man. He had no bad temper any more, was patient, long-suffering, full of love for his fellow man etc.
Rev Spurgeon didn't stop his conversation but picked up his glass of water and threw it in the man's face, who burst out in a loud stream of profanities.
The pastor who told this a few years ago said: "Now THAT's the way to test a person's faith!"