Puritan Thomas Manton in his commentary on Jude made the following application from verse 3 and his words from centuries ago speak to us today and our need for fellowship and community as the body of Christ:

This shows how inappropriate it was for religion to be confined to a cloister or wrapped in a black garment or consigned to what was called a religious house. Oh, how far this was from the modesty of the apostles! Peter called the faith of ordinary Christians “a faith as precious as ours” (2 Peter 1:1), and Jude speaks of the salvation we share. The Jews who lived before them confined God’s choice to their nation. They could not bear to hear about salvation among the Gentiles or of a righteousness that came to everyone and on all who believe. We are envious by nature and want to appropriate common favors to ourselves. The church of Rome seeks to bring the whole world under their law and confine truth and faith and salvation within the precincts of their churches. They seize the keys of heaven and open the gate to whomever they wish. Now God has broken down all enclosures that attempt to build up a new wall of separation. Corrupt human nature does not want other people to share the same privileges that we have. People value their lesser differences and the particular opinions they have taken up as if only those of their own party and persuasion could be saved; it is our nature to treat our own opinions as holy, and not to admit that anyone is good unless they agree with us in everything. There were divisions in Corinth. Even the people who said, “I follow Christ” made themselves into a faction (see 1 Corinthians 1:12). We are apt to be harsh toward those who differ from us and to be happy only with those who share our opinions. Beware of hurting your Christian brother. “Why do you look down on your brother?” (Romans 14:10). Since God has made him a Christian, why do you make nothing of him? And why do you make another religion out of all your private opinions as if nobody could be a saint or a believer unless they thought exactly as you do? Beware that you do not fence in the common salvation; enclosures are against the law.

I think the words of Thomas Manton speak for themselves…