Examine yourselves is a command from the Scripture. It is both healthy and profitable to periodically behold the Image of Christ in the Scripture in order to see if His dying and His life are manifestly both present and growing in you.
"The Corinthian believers, confident of their own wisdom, had been blissfully testing Paul and other claimants to apostleship; but they should have been testing themselves. … The word “yourselves” is emphatic in position: yourselves, as opposed to everybody else. … Now if the Corinthians are truly Christian, they will realize that Christ Jesus is in them-unless, or course, they fail the test. If Christ Jesus is in them, then they, like Paul, should hunger to know something of Christ’s meekness and gentleness, something of his weakness. Like Paul, they will pursue not only the power of his resurrection but also “the fellowship of sharing in his sufferings, becoming like him in his death” (Phil. 3:10). That is what they must inevitably come to recognize – unless of course they fail the test. … Since in his metaphor they administer the test to themselves, they are unlikely to fail themselves. The logic of Paul’s entire presentation, however, demands that if they “pass” themselves, they must pursue the crucified Christ as diligently as they pursue the exalted Christ. The only alternative is that they fail the test. ... In short, when a person is broken in spirit and contrite before the God of all justice, grace comes and pronounces absolution and grants confidence. But when a person is haughty and arrogant, the product of well-cultivated triumphalism, unconscious of grace or of any need for it, then grace flees and a stern apostle warns, “Examine yourselves to see whether you are in the faith; test yourselves.” There are millions of professing believers in North America today (to say nothing of elsewhere) who at some point entered into a shallow commitment to Christianity, but who, if pushed, would be forced to admit they do not love holiness, do not pray, do not hate sin, do not walk humbly with God. They stand in the same danger as the Corinthians; and Paul’s warning applies to them no less than to the Corinthian readers of this epistle." (Carson, A Model of Christian Maturity, 182-183, 184).
The gospel that has saved every believer is the same gospel that is saving every believer. The same gospel that is saving is also the same gospel that will ultimately save every believer. Thanks be unto Christ Jesus for His saving grace!