A Little Inconsistent in the Objection

"A second objection [that the general call of the gospel is not a bona fide call] is derived from the spiritual inability of man. Man, as he is by nature, cannot believe and repent, and therefore it looks like mockery to ask this of him. But in connection with this objection we should remember that in the last analysis man’s inability in spiritual things is rooted in his unwillingness to serve God. The actual condition of things is not such that many would like to repent and believe in Christ, if they only could. All those who do not believe are not willing to believe, John 5:40. Moreover, it is no more unreasonable to require repentance and faith in Christ of men than it is to demand of them that they keep the law. Very inconsistently some of those who oppose the general offer of salvation on the basis of man’s spiritual inability, do not hesitate to place the sinner before the demands of the law and even insist on doing this." 

Systematic Theology – Louis Berkhof