Jesus admonished is to
remain in Him.
- If anyone does not abide in Me, he is cast out as a branch and is withered; and they gather them and throw them into the fire, and they are burned. John 15:6
At the time, Jesus was speaking to a mixed multitude, including those who believed and those who didn't. The warnings in John 15 are for those who either were denying Christ or at least skeptical. Those were not warnings to those who were born again which would soon occur under the New Covenant Jer 31:31-
We abide and keep His Commandments because of the new birth not in order to remain in Him.
The “way” this same John instructs us, by the Spirit to remain in Christ, is to obey Him; to keep His commandments.
- Now he who keeps His commandments abides in Him, and He in him. And by this we know that He abides in us, by the Spirit whom He has given us. 1 John 3:24
That is for fruit bearing, not for salvation. That same John makes crystal clear recording what is needed for salvation...
He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
(Joh 3:18)
Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation;
but is passed from death unto life.
(Joh 5:24)
And this is the record, that God hath given to us eternal life, and this life is in his Son.
He that hath the Son hath life; and he that hath not the Son of God hath not life. These things have I written unto you that believe on the name of the Son of God; that
ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. (1Jn 5:11-13)