Matthew is very concerned in his gospel with the unity of the
Christian community. He does not envision the Church as an
exclusionary organization, but rather as an inclusive community
which is guided by the spirit of the parable of the weeds.
This attitude of acceptance is also in line with the revelation of God “as merciful and gracious, slow to anger, abounding in kindness.”
An inclusive Church that is kind and lenient toward its own members and toward everyone else should be an inspiration to a divided world that has a tendency to judge harshly, to be quick to anger, and to uproot weeds even at the cost of damage to the good plants.
By virtue of her mission to shed on the whole world the radiance of the gospel message, and to unify under one Spirit all men of whatever nation, race, or culture, the Church stands forth as a sign of that brotherliness which allows honest dialogue and invigorates it.
Such a mission requires in the first place that we foster within the Church herself mutual esteem, reverence, and harmony, through the full recognition of lawful diversity.
Vatican II, Constitution on the Church in the Modern World, 1965:92.