John here reminds his readers of the gospel message they first heard. It is first and foremost a call to remember. To remember the truth of the gospel message as they first heard it and to allow that to bring them fellowship with the Son and the Father. As someone who has been following Jesus for some time now, from time to time I need to remember the joy of my salvation when I first came to know Jesus. I need to remember myself as that kid who finally understood that there was a God who unconditionally loved me and wanted something better for me. This childlike wonder and awe of a God who loved me so much that he gave his one and only Son centers me in my identity as a child of God. This centering of my identity allows me to walk in fellowship with the Father, abiding in his loving presence. It is in this call to remember that John seeks to lift his readers’ gaze above the confusion, noise, and deception of our current days and remind them of the free gift of eternal life with the Father that is to come.
"Let what you heard from the beginning abide in you. If what you heard from the beginning abides in you, then you too will abide in the Son and in the Father. 25 And this is the promise that he made to us—eternal life."
1 John 2:24-25