How can a person undervalue, but also overvalue, Church Visible membership?
Article 28 of the Belgic Confession of Faith very clearly and powerfully states the duty of everyone to join the church.
BELGIC CONFESSION OF FAITH - Article 28
That every one is bound to join himself to the true church
We believe, since this holy congregation is an assembly of those who are saved, and that out of it there is no salvation, that no person of whatsoever state or condition he may be, ought to withdraw himself, to live in a separate state from it; but that all men are in duty bound to join and unite themselves with it; maintaining the unity of the church; submitting themselves to the doctrine and discipline thereof; bowing their necks under the yoke of Jesus Christ; and as mutual members of the same body, serving to the edification of the brethren, according to the talents God has given them. And that this may be the more effectually observed, it is the duty of all believers, according to the Word of God, to separate themselves from all those who do not belong to the Church, and to join themselves to this congregation, wheresoever God hath established it, even though the magistrates and edicts of princes were against it, yea, though they should suffer death or any other corporal punishment. Therefore all those, who separate themselves from the same, or do not join themselves to it, act contrary to the ordinance of God.
Membership in the Church Invisible is necessary for salvation without this no man can or will be saved. Each of the seven reasons listed for church membership on the previous page applies primarily to the church's spiritual members, to the Church Invisible. However, each reason also has an outward aspect, benefit, and responsibility, for all Church Visible members.
The seven outward benefits of Church Visible membership are as follows:
1. Worship - places the person in the way of outward obedience to God's command to gather together to worship Him on the weekly Lord's Day
2. Instruction - brings one under the proclamation of God's Word, the warnings of His law, and the invitations of His gospel, the means through which God has promised to work salvation
3. Prayer - includes the person in the prayers of the church
4. Communion - brings the person in contact with God's children