The parable of the net let down into the sea has some points in common with that of the wheat and the tares (Matthew 13:47-52). It is intended to instruct us on a most important subject: the true nature of the visible Church of Christ.
The preaching of the gospel was the letting down of a large net into the midst of the sea of this world. The professing church it was meant to gather together was to be a mixed body. Within the folds of the net, there were to be fish of every kind, both good and bad. Within the bounds of the Church there were to be Christians of various sorts, unconverted as well as converted, false as well as true. The separation of good and bad is sure to come at last, but not before the end of the world. Such was the account the great Master gave to His disciples of the churches they were to found.
It is of the utmost importance to have the lessons of this parable deeply engraved on our minds. There is hardly any point in Christianity on which greater mistakes exist than the nature of the visible Church. There is none, perhaps, on which mistakes are so perilous to the soul.
Let us learn from this parable, that all congregations of professed Christians ought to be regarded as mixed bodies. They are all assemblies containing "good fish and bad," converted and unconverted, children of God and children of the world, and ought to be described and addressed as such. To tell all baptized people that they are born again and have the Spirit and are members of Christ and are holy in the face of such a parable as this is utterly unwarrantable. Such a mode of address may flatter and please. It is not likely to profit or save. It is painfully calculated to promote self-righteousness and lull sinners to sleep. It overthrows the plain teaching of Christ, and is ruinous to souls. Do we ever hear such doctrine? If we do, let us remember "the net."
Adapted from The Gospel of Matthew by J.C. Ryle (Chapter 13).