en_tn_lite_do_not_use/1jn/02/24.md

As for you

In 2:24-26 the word "you" is plural and refers to the people John is writing to. (See: rc://en/ta/man/translate/figs-you)

let that which you have heard from the beginning remain in you

"remember and believe what you have heard from the beginning." How they heard it, what they heard, and what "the beginning" means can be made explicit: “continue to trust what we have taught you about Jesus just as you have trusted since you first became believers.” (See: rc://en/ta/man/translate/figs-explicit)

that which you have heard from the beginning

This can be translated as "what we taught you about Jesus when you first became believers."

If that which you heard from the beginning remains in you

"If you continue to trust what we taught you"

also remain in the Son and in the Father

See how this was translated in 1 John 2:4

And this is the promise which he promised us; eternal life

"And this is what he promised to give us; eternal life" or "And he has promised to cause us to live forever."

he promised us

Here the word "he" is emphatic and refers to Christ. The word "us" refers to John and all believers, including those he was writing to. (See: rc://en/ta/man/translate/figs-inclusive)

would lead you astray

"would try to make you believe a lie" or "want to draw you away from God and His truth"