Abiding in Christ
The primary reference is in John 15:1-8, which describes the relationship that exists between God and believers. Those that neglect to abide in Him are cast out and in danger of judgment (Matthew 7:21-23). Those that do abide in Christ are not only considered true disciples, but their lives will produce much fruit (Galatians 5:22, 23). The Christian must believe and abide in Christ. The word 'believe' in the following passages and others such as John 3:16; John 6:40, is in the present tense, and means “to believe and to continue to believe” or “to abide.” It implies not only an initial act of faith, but a maintained attitude. Even though God does not desire that anyone should perish for all eternity, God does not save or keep a man against his will.
Just as faith in God and repentance from sin are necessary for salvation, so they are necessary for the continuance of the Christian’s life. The scriptural condition for salvation is, believing. “He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him” (John 3:36). Also, “He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God” (John 3:18).