Not all Israel is Israel

Following up the reading of Doug Wilson's Against the Church, the following excerpt from the Second Helvetic Confession emphasizes the mixed nature of the visible church and the need for personal faith.

NOT ALL WHO ARE IN THE CHURCH ARE OF THE CHURCH. Again, not all that are reckoned in the number of the Church are saints, and living and true members of the Church. For there are many hypocrites, who outwardly hear the Word of God, and publicly receive the sacraments, and seem to pray to God through Christ alone, to confess Christ to be their only righteousness, and to worship God, and to exercise the duties of charity, and for a time to endure with patience in misfortune. And yet they are inwardly destitute of true illumination of the Spirit, of faith and sincerity of heart, and of perseverance to the end. But eventually the character of these men, for the most part, will be disclosed. For the apostle John says: "They went out from us, but they were not of us; for if they had been of us, they would indeed have continued with us" (I John 2:19). And although while they simulate piety they are not of the Church, yet they are considered to be in the Church, just as traitors in a state are numbered among its citizens before they are discovered; and as the tares or darnel and chaff are found among the wheat, and as swellings and tumors are found in a sound body, And therefore the Church of God is rightly compared to a net which catches fish of all kinds, and to a field, in which both wheat and tares are found (Matt. 13:24 ff., 47 ff.).