One of Paul Williams favorite claims is that there is no mediator between God and man in Islam. Then he tries to prove that this is the same teaching of the bible by citing the following passage:
The Pharisee and Tax Collector
Luke 18 v 9 And he spake this parable unto certain which trusted in themselves that they were righteous, and despised others: 10 Two men went up into the temple to pray; the one a Pharisee, and the other a publican. 11 The Pharisee stood and prayed thus with himself, God, I thank thee, that I am not as other men are, extortioners, unjust, adulterers, or even as this publican. 12 I fast twice in the week, I give tithes of all that I possess.13 And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner. 14 I tell you, this man went down to his house justified rather than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted.
Williams concludes that man is justified by simply calling upon God for mercy.
The reason why I believe that Williams is wrong is that both these men are Jews living under the covenant of Moses. One is a publican and the other is a Pharisee. However they are both Jews living under the Mosaic covenant. That means that they both approach God through Moses as their mediator and the priesthood which Moses established according to the laws that God gave him at Mt. Sinai.
The mercy which the publican entreats from God is a mercy which is channeled through the temple and the priesthood, to which the context clearly alludes; a mercy which God could not otherwise bestow, having ordained these things as necessary for salvation, being themselves the signs of the perfect Great High Priest Jesus Christ and his blood sacrifice.