As far as "abiding in Christ" goes...it's a promise of our being in Him forever because of His finished work for us - not a "conditional" as works-based mindsets want us to believe.
Paul uses the phrase "in Christ, in Him, etc" - 146x times in his writing of all his books. We believers are in Christ and He does not throw us away into hell or the lake of fire as the works-based mindsets try to deceive us with.
Fruit is love, joy, peace, patience, etc. All 9 fruit of the Spirit Paul talked about in Gal.5
John 8:35 (NASB)
[SUP]35 [/SUP] "The slave does not remain in the house forever; the son does remain forever. ( remain = same Greek word " abide " used in John 15 )
1 John 3:2 (KJV)
[SUP]2 [/SUP] Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
John 14:16-17 (NASB)
[SUP]16 [/SUP] "I will ask the Father, and He will give you another Helper, that He may be with you forever; ( "with you" is the same Greek word as "abide" used in John 15 )
[SUP]17 [/SUP] that is the Spirit of truth, whom the world cannot receive, because it does not see Him or know Him, but you know Him because He abides with you and will be in you. ( same word used in John 15 about "abiding in Christ" )
Jesus is the Truth and He abides in us forever!
1 John 4:15 (NASB)
[SUP]15 [/SUP] Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. ( same word used here "abides" as in John 15 - abides )
2 John 1:2 (NASB)
[SUP]2 [/SUP] for the sake of the truth which abides in us and will be with us forever: ( forever is a very long time - same word "abides" as in John 15 - abides )