The Gospel passage is framed (before) with the Parable of the Lost Sheep, and (after) the Parable of the Unforgiving Debtor — both of which dramatise the conviction that God's desire is that the sinner be saved, not condemned. The community's power to exclude members is a last resort. The community members are to follow the example of Jesus whose favourite image of himself is that of a Shepherd seeking lost, straying sheep. Their aim should always be to win the erring Christian back into the community. Excommunication i.e., treating them as tax-collectors, sinners, gentiles is only intended to shock the offender into reconciliation.
There are 3 steps to be taken when one member sins against another, (not petty squables). Each step or stage is to be a means of evangelising the re-calcitrant member into "re-membering" with the community. The three steps are: 1) personal discussion, 2) discussion before witnesses, 3) discussion before the whole community.
People seek God in temples, churches, shrines, in contemplating nature, in finding peace within! But God wants us to first seek his presence in the Christian community. He is present in our prayer together, in our discussions, in our problems and crisis.
God is not contained in things, in shrines and holy pictures etc. The community is the sacrament of God's presence; our faithfulness to community is a sign we are in God's all-embracing Grace!
Lord, it is only in You, we find life and fulfilment.