What does Jude mean by common salvation?

In Jude 1:3, the term 'common salvation' signifies a mutual faith shared by all true believers, emphasizing that the essential truths of the gospel remain constant and unchanged throughout time. This commonality speaks to the shared experience of all who have been called and sanctified by God. Jude encourages recipients of his letter to earnestly contend for this faith, underscoring its irreplaceability and the necessity of vigilance against teachings that seek to distort or dilute the true gospel of grace.