A  ²⁴ Therefore let that abide in you

B  which you heard from the beginning.

B’  If what you heard from the beginning

A’  abides in you,

C  you also will abide in the Son and in the Father. ²⁵ And this is the promise that He has promised us—eternal life.

A:  Abiding in Him.  
B:  You have heard this from the beginning.  
C:  The Promise: He abides in you, and you will have eternal life.