1. Because God often declares his detestation and abhorrence of others being there, and manifests his indignation against them. As to the man that came to the marriage supper without the wedding-garment, Matt. xxii. 11-13; and the five foolish virgins, chap. xxv.; and the dreadful end of the tares, chap. xiii. 38-44, which were the hypocrites, that by the devil's instigation had crept into the Church. It is true that such were, and will be, in the best of churches, although their guides may do all they can to prevent it, because they cannot make an infallible judgment of persons' states; yet it is as certain these are usurpers and ought not to be there. For, although they are in God's providence permitted to creep in, yet we may be sure they are not there with his approbation:--they are not all Israel that are of Israel; for, saith God to all uncircumcised, What have you to do to take my covenant into your mouth, seeing you hate instruction and cast my words behind your back, (as all hypocrites do,) Ps. l. 16, 17. And Christ says, that such as will not have him to reign over him (and to be sure hypocrites will not) shall be destroyed, Luke xix. 27. Now, as hypocrites are most loathsome and abominable persons in the sight of God, as may be seen at large in Matt, xxiii. 13-35, they have no right unto the spiritual privileges of the Church of Christ, because, in the sight of God, the gospel Church should consist only of new creatures and real members of Jesus Christ. II. That all church members ought to be sincere-hearted believers appears by the high titles which the Lord Jesus gives unto them in Scripture: they are described to be like the king's daughter, all glorious within. They are called saints, holy brethren, and beloved, elect, dear children of God, the spouse of Christ, a holy temple of God, lively stones, built up a spiritual house, a holy priesthood, and the Lord's sealed ones. Now such honorable titles belong not unto mere formal professors, but only unto the real members of Christ: not unto those that have a name only; but to such as are so indeed and in truth.