What does it mean to "abide" in Christ?
Jesus defined "Abiding in Christ" when He likened Himself to a grapevine and believers to its branches: "Abide in Me, and I in you. As the branch cannot bear fruit of itself, unless it abides in the vine, so neither can you, unless you abide in Me" (John 15:4). That picture illustrates the vital union existing between Christians and Jesus Christ.
The word "abide" basically means "to remain." Every Christian remains inseparably linked to Christ in all areas of life. We depend on Him for grace and power to obey. We look obediently to His Word for instruction on how to live. We offer Him our deepest adoration and praise and we submit ourselves to His authority over our lives. In short, Christians gratefully know Jesus Christ is the source and sustainer of their lives.
Abiding in Christ evidences genuine salvation. The Apostle John alluded to that when he referred to defected professors who "went out from us, but they were not really of us; for if they had been of us, they would have remained with us; but they went out, in order that it might be shown that they all are not of us" (1 John 2:19).
People with genuine faith will remain--they won't defect; they won't deny Christ or abandon His truth. Jesus reiterated the importance of abiding as a sign of real faith when He said, "If you abide in My Word, then you are truly disciples of Mine" (John 8:31).
For more information on this subject, see John's audio series Abiding in Christ.