Yes, these are great verses that outline elements of the Gospel.
Romans 6 discusses the Purpose of Christ.
2 Cor also outlines the Purpose of Christ.
John 3 also outlines the Purpose of Christ.
There are two other Elements to the Gospel that we also need to be aware of, thus, the passages that you have provided are not the Gospel, but part of the Gospel.
The reason why we are told to Ask, Seek, and Knock, is because the Gospel is given to us in small pieces here and there. It seems (to me) that when Paul disclosed the concept of the Mysterious Plan of God, this should be an indicator that there is more going on than what we had originally thought. Speaking for myself, when I read of Paul making this disclosure in Ephesians chapters three and two (best to read in that order), my "detective-like" mind finally caught onto that concept . . . thus I set out to try to understand, exactly, what Paul meant by those statements. And so in my studies of the entire Bible, I came to realize that it was True, that there was much more going on regarding the Gospel than I had ever imagined. For the first time in my life, after thousands of hours of study, the Gospel finally became clear to me.
What I found is that when I could give a conspicuous, detailed outline of the three points below, that was the moment when I, for the first time in my near 55-year life, was finally able to explain the True Gospel to another person. Prior to this moment of discovery, I was only able to give the bits and the pieces . . . which explains why I hadn't ever really given the Gospel to anyone. Had anyone asked me to explain the Gospel to them, I would have stumbled, for the "church" does not offer any classes on how to effectively transmit the Gospel to another person. Yes, I'm speaking in general terms, as I'm sure that there is a Church out there, somewhere, that has such classes, but I've been around the christian block for many decades and in my experience, the church is not taking the Gospel seriously. If I were a Pastor, or held any effective teaching role in a church, be it even a 1st grade class, my students would immediately begin to be taught the True Gospel of Jesus Christ. I would help to flush down the toilet their nominal view.
Until I was able to explain in the detail the three below points, I was virtually incapable of explaining the Gospel to anyone. They are:
1) The Purpose of Christ.
2) The Work of Christ.
3) The Effect of Christ.
I'm not smart at all. I'm not special. I'm not gifted. And certainly, the Lord does not require me in any sense whatsoever. All that I did was ask myself, "What is the True Gospel?" And then, with that question in mind, I began reading and cataloging ever passage in the Bible that might answer that question. And so that is what I have done, reading the Bible in a timeline, chronological order so that I might understand the Gospel, or, the Story of God.
There is only one Gospel, and it is fortunately very simple - believe on the Lord Jesus, and you shall be saved.
John 6:28-64
28 Then said they unto him, What shall we do, that we might work the works of God?
29 Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. 30 They said therefore unto him, What sign shewest thou then, that we may see, and believe thee? what dost thou work? 31 Our fathers did eat manna in the desert; as it is written, He gave them bread from heaven to eat. 32 Then Jesus said unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven. 33 For the bread of God is he which cometh down from heaven, and giveth life unto the world. 34 Then said they unto him, Lord, evermore give us this bread.
35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst. 36 But I said unto you, That ye also have seen me, and believe not.
37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out. 38 For I came down from heaven, not to do mine own will, but the will of him that sent me. 39 And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day.
40 And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day. 41 The Jews then murmured at him, because he said, I am the bread which came down from heaven. 42 And they said, Is not this Jesus, the son of Joseph, whose father and mother we know? how is it then that he saith, I came down from heaven? 43 Jesus therefore answered and said unto them, Murmur not among yourselves. 44 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day. 45 It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me. 46 Not that any man hath seen the Father, save he which is of God, he hath seen the Father.
47 Verily, verily, I say unto you, He that believeth on me hath everlasting life. 48 I am that bread of life. 49 Your fathers did eat manna in the wilderness, and are dead. 50 This is the bread which cometh down from heaven, that a man may eat thereof, and not die. 51 I am the living bread which came down from heaven: if any man eat of this bread, he shall live for ever: and the bread that I will give is my flesh, which I will give for the life of the world. 52 The Jews therefore strove among themselves, saying, How can this man give us his flesh to eat?
53 Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you. 54 Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day. 55 For my flesh is meat indeed, and my blood is drink indeed. 56 He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him. 57 As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me. 58 This is that bread which came down from heaven: not as your fathers did eat manna, and are dead: he that eateth of this bread shall live for ever. 59 These things said he in the synagogue, as he taught in Capernaum. 60 Many therefore of his disciples, when they had heard this, said, This is an hard saying; who can hear it? 61 When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you? 62 What and if ye shall see the Son of man ascend up where he was before?
63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life. 64 But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him.