And a scholar of the Law stood up and put Him to the test, saying, "Teacher, what shall I do to inherit eternal life?"
He said to him, "What is written in the Law? How do you read it?"
And he answered, "You shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind, and your neighbor as yourself."
And He said to him, "You have answered correctly; do this, and you will live."
(Lk 10: 25-28)
After reading this passage, many Christians - RC, EO and Protestant alike - if it were not for the fact that they have got used to reading it, would probably feel the impulse of jumping and saying to the Lord: "Wait a moment Lord, You have not mentioned faith in You and baptism! How can anyone inherit eternal life without first believing in You as the Eternal and Consubstantial Son of God and being baptized in your Name? RCs and EOs certainly believe that, after that, the faithful must love God and neighbor to remain partakers of divine life (1 Jn 3: 15,17), but they must first believe and be baptized to become that!"
The problem for those hypothetical startled Christians is that there is another passage in which the Lord said the same thing, even more clearly:
And someone came to Him and said, "Teacher, what good thing shall I do that I may obtain eternal life?"
And He said to him, "Why are you asking Me about what is good? There is only One who is good; but if you wish to enter into life, keep the commandments."
He said to Him, "Which ones?" And Jesus said, "You shall not murder, You shall not commit adultery, You shall not steal, You shall not bear false witness, Honor your father and mother, and, You shall love your neighbor as yourself."
(Mt 19: 16-19)
Again, the startled Christian would object: "Wait a moment Lord, those are the requirements to remain in eternal life (for RCs and EOs, at least), not to enter into it! We can obtain eternal life only by believing in You as the Son of God and being baptized!"
The beginning of the solution to this problem is precisely in the differencial text in the other two versions of the second passage, i.e. those of Mark and Luke:
A ruler questioned Him, saying, "Good Teacher, what shall I do to inherit eternal life?"
And Jesus said to him, "Why do you call Me good? No one is good except God alone.
(Lk 18: 18-19)
While a trivial first reading of this passage is that Jesus denies his divinity, an enlightened reading is that Jesus is saying: "Why do you call Me good, if you have NOT yet come to know that I and the Father are one (Jn 10: 30), the same and only "I Am" of Ex 3: 14? No one is good except God alone." With this reading, it becomes clear that the quoted first part of Jesus' answer to the young rich person, or "ruler", is that which applies to any person of good will who, through no fault of their own, does NOT know that Jesus is the Consubstantial Son of God. Which was also the case of the scholar of the Law in the first passage. Any such persons "who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience (enlightened, in the case of the people in the quoted passages, by the divinely revealed commandments) – those too may achieve eternal salvation." (LG 16)