“Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed;” — John 8:31
Must of life is based on various levels of distrust. That’s why there are inspections, contracts and laws. If everyone could be trusted to do the right thing, then they would be unnecessary. Unfortunately, not everyone who expresses interest or a level of belief in Jesus can be trusted to be genuine.
Even Jesus knew this. That’s why He said to the Jews which believed on Him, “If ye continue in my word, then are ye my disciples indeed.” He was saying, “If you are really and truly my disciples, this won’t be just a passing interest. You will continue to listen, believe, and obey my Word. And my Word will eventually lead you to truth and to freedom from sin.”
This is not saying that salvation comes as a process or is a result of our continuing to obey, but it is showing that faith in Christ is more than just a passing, quick decision. It requires hearing the gospel, understanding the gospel, and getting enough of the Word to realise who Christ, what sin is, and what the truth is and then responding to that truth in faith.
There is a sense in which this could be applied to the Christian as well. If we are truly saved, then we should behave like true disciples. We should be in the Word, reading it, believing it, and obeying it. It is the message of freedom, “the perfect law of liberty” as James puts it!