Salvation is the rescue from wrath. It is the necessity without which you cannot escape the wrath of God. But God has offered it freely through Jesus Christ.
This discussion is not about judging other peoples' salvation. It is a crucial discussion to have with people especially now that many things have become very superficial, including the profession of faith.
Those who are used to doing something to earn something misunderstand salvation by faith. This article explains WHY you need to be saved, and how to be saved.
The Bible is clear that a person must hear and believe the gospel to be saved. This makes the knowledge of the gospel the most important thing in the Bible, and therefore the most important knowledge you can have.