To the best of my understanding, this would be the Christian answer to your question, I hope that it is an accurate account of how Christians view salvation.
All Scripture is quoted from the King James translation.
Since you mentioned in your question what Jesus said to the young lawyer, let's see what else we can find that Jesus told others about being saved.
To start, let's begin with what Jesus told Nicodemus about being born again;
John 3:5 through 8 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. Marvel not that I said unto thee, Ye must be born again. The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.
From that passage. It appears that there is a whole lot more to being saved and simply loving others, although that is a large part of it. And so salvation seems to be something called being born again, and pray exactly what does that mean?
As Jesus said we apparently must have two births the first birth would be the physical birth, and the other as he said, is a spiritual birth. So what exactly is a spiritual birth. This is not as easy to understand. As I said the first is a physical birth which we all understand we are born, grow up and become adults. Spiritual birth is not that much unlike physical birth. We are reborn, or born again in Jesus Christ and we progress from being an infant in Christ to becoming more and more like him.
So why are we quoting Jesus, when what we want to know is what it takes for salvation?
Mathew 1:21 And she shall bring forth a son, and thou shalt call his name Jesus: for he shall save his people from their sins.
From that passage, it appears that Jesus is the way salvation. And if he being the way to salvation. He would therefore have all of the keys to the kingdom. The question then becomes how is this accomplished?
John 3:16 and 17 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
As Jesus said in John 3:16 whosoever believe with in him should not perish but have everlasting life. So exactly what does that entail? Let's take a look at some Scripture and see if we can determine what it does really mean.
Let's go back to what Jesus said to Nicodemus;
John 3:14 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: that whosoever believeth in him should not perish, but have eternal life.
What this refers to is:
Numbers 21:5 through 9 And the people spake against God, and against Moses, Wherefore have ye brought us up out of Egypt to die in the wilderness? for there is no bread, neither is there any water; and our soul loatheth this light bread. And the LORD sent fiery serpents among the people, and they bit the people; and much people of Israel died. Therefore the people came to Moses, and said, We have sinned, for we have spoken against the LORD, and against thee; pray unto the LORD, that he take away the serpents from us. And Moses prayed for the people. And the LORD said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live. And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.
Jesus further expounded on that in:
John 12:32 And I, if I be lifted up from the earth, will draw all [men] unto me.
Here Jesus is saying that after he has conquered death. Through his resurrection then all mankind will be drawn to him for salvation.
So how do we know that Jesus was including us and not just a specific group of people?
John 4:22 Ye worship ye know not what: we know what we worship: for salvation is of the Jews.
Jesus is telling the woman at the well that he came to proclaim salvation to the Jews.
But the Jews did not wholly accept him and so:
Matthew 23: 37 O Jerusalem, Jerusalem, [thou] that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under [her] wings, and ye would not!
John 5:40 And ye will not come to me, that ye might have life.
He opened the door to salvation to all the World!
Mark 16:15-16 And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
But there is more to it than just believing that Jesus death and resurrection, is all it take because he added;
Luke 24:47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
Luke 13:29-30 And they shall come from the east, and [from] the west, and from the north, and [from] the south, and shall sit down in the kingdom of God. And, behold, there are last which shall be first, and there are first which shall be last.
So how do we know it was for our sins?
Mark 2:17 When Jesus heard [it], he saith unto them, They that are whole have no need of the physician, but they that are sick: I came not to call the righteous, but sinners to repentance.
John 10:16 And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, [and] one shepherd.
John 11:51-52 And this spake he not of himself: but being high priest that year, he prophesied that Jesus should die for that nation; And not for that nation only, but that also he should gather together in one the children of God that were scattered abroad.
John 6:37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out.
So does this mean just anyone will go to heaven?
Matthew 22:14 For many are called, but few [are] chosen.