"How faithful" does your wife expect you to be to her? That is what the Lord expects, too "For I am jealous over you with godly jealousy: for I have espoused you to one husband, that I may present you as a chaste virgin to Christ" (2 Corinthians 11:2). Your wife would not like it, if, after telling you that she has been faithful to you, you were to ask her, "How faithful?"
"How faithful?" Children of God are to "cleanse (themselves) of all filthiness of the flesh and spirit," and be "blameless and harmless, the sons of God, without rebuke in the midst of a crooked generation among whom (they) shine as lights in the world" (2 Corinthians 7:1; Philippians 2:15).
You asked, "is salvation based on being faithful?" "Be thou faithful unto death, and I will give thee a crown of life" (Revelation 2:10). Will Christ give a man a crown of life, even if he is not faithful? Further, "it is required in stewards that a man be found faithful" (1 Corinthians 4:2). The key word in that passage is, "required." What does "required" mean, William? It means "necessary," or "essential," does it not? Thus, to be saved, to have a crown of life, it is "required" that a man be found faithful.
How will Christ reward a steward who does not do that which is "required"? The answer to that question is found in Luke 12:42-46:
Observe that the "blessed servant" is the one who is found doing as instructed. If the Lord's servant becomes an unfaithful steward, he is appointed a "portion with the unbelievers." What will happen to all "unbelievers"? They "shall have their part in the lake which burneth with fire and brimstone: which is the second death" (Revelation 21:8). That is, they will go to hell. That is where unfaithful stewards are going, too, for the Lord will appoint them a portion "with the unbelievers." Even though Baptist doctrine says that an unfaithful steward is saved just as well as the faithful one, the passages above show that doctrine to be false.
"Be thou faithful unto death," for it is only the faithful who will hear the welcome words, "well done, thou good and faithful servant" (Matthew 25:21).