Okay, then I feel free to examine some points you ... (
It was just some thoughts that occurred to me, inspired by the thoughts you posted with your topic.
Instead of just saying no, I don't think altruism is possible, I wrote what I considered a more thought provoking way to put it. If the thoughts strike a chord with you, fine, if they don't, just take the literal response that I don't think altruism is possible.
Here is my response to the scriptures you listed.
In that day you will know that I am in My Father, and you in Me, and I in you. -- Who is you? You is a chosen child of God who has trusted Christ for salvation. I am not sure how you intend this to relate to selflessness or altruism. A child of God would want a close relationship with God, and God says He wants that for His children.
4 Abide in Me, and I in you. As the branch cannot bear fruit of itself unless it abides in the vine, so neither can you unless you abide in Me. 5 I am the vine, you are the branches; he who abides in Me and I in him, he bears much fruit, for apart from Me you can do nothing. 6 If anyone does not abide in Me, he is thrown away as a branch and dries up; and they gather them, and cast them into the fire and they are burned. 7 If you abide in Me, and My words abide in you, ask whatever you wish, and it will be done for you. -- Same response as above. This is not about selflessness, it is about appealing to a person's love of self. If you want to maintain your life, and the good God can do for you, you will abide in Him.
26 and I have made Your name known to them, and will make it known, so that the love with which You loved Me may be in them, and I in them. -- Here Jesus is thanking God that a few in the world that God sent to Him are capable of knowing Him and Him knowing them. In the previous verse Jesus acknowledges that the majority of the world does not know Him, but these few chosen by God can know Him.
9 However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. 10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. -- This the same message as John 3:3-8, that we must be born of the Spirit to have a relationship with God. Anyone not born again, of the Spirit, does not belong to Him and will not come to Christ willingly. If the Spirit of God does not dwell in you, you are in the flesh and will die in sin with the body.
1 Corinthians 6:17
17 But the one who joins himself to the Lord is one spirit with Him. --Without context, this verse can't be understood. The context is of not using your body for sinful purposes. The meaning is similar to Jesus' statement that we will know them by their fruits. We can know that one is one spirit with the Lord if he avoids sin. If we are one spirit with the Lord, we will not sin, because the Lord is Holy, and no part of His body would be allowed to remain in sin.
2 Corinthians 1:21
21 Now He who establishes us with you in Christ and anointed us is God, 22 who also sealed us and gave us the Spirit in our hearts as a pledge. -- This is saying that God chose and annointed the Christians, and gave them spiritual life. Christians exist because God chose them, not because they choose God.
2 Corinthians 5:17, 21
17 Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. 18 Now all these things are from God, who reconciled us to Himself through Christ 21 He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him. -- Again this is a way of distinguishing Christians by their fruits. A true Christian will exhibit a new nature, and be a new creature. That can only occur by God intervening and acting in that person's life. Other humans can't know of the inward actions of the Spirit in someone's life, but we can only see the outward signs that something has changed. God is the actor, and we receive the benefit, if He chooses us. In verse 21, who are we who Christ was made to be sin on our behalf? Chapter 1 tells us that Paul was writing to the church of God which is at Corinth with all the saints. So Christ was made to be sin on behalf of the Church of God and the saints.
13 until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a mature man, to the measure of the stature which belongs to the fullness of Christ. -- This is talking about attaining maturity in the Christian faith. Again, this verse cannot stand alone, but must be read in context. He is talking about different Christians using their different gifts to help everyone grow and mature, and ultimately achieve the fullness of the body of Christ that God planned.
27 to whom God willed to make known what is the riches of the glory of this mystery among the Gentiles, which is Christ in you, the hope of glory. -- This is the end of a very long sentence. The entire sentence says that Paul and other saints were told mysteries of the gospel and entrusted by God to make those mysteries known to the Gentiles and the whole world. Paul says he follows God's command to teach in spite of the suffering he endures in the process.
3 For you have died and your life is hidden with Christ in God. -- This is speaking to the chosen who have been raised up with Christ. They have died, and are alive now only because of the mercy of God. The next verse says Christ is our life, so we will be revealed with Him in glory only because of Him choosing us and giving us the new spiritual life.
1 John 2:24
24 As for you, let that abide in you which you heard from the beginning. If what you heard from the beginning abides in you, you also will abide in the Son and in the Father. -- This is another teaching of how to know whether or not one is truly saved. Many claim to be saved and want to be saved, but only the ones who abide in the Son and the Father are truly saved.
1 John 4:16
16 We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him. -- This is another teaching of how to know whether or not one is truly saved. Many claim to be saved and want to be saved, but only the ones who abide in God are truly saved. This is not a formula for achieving salvation, it is merely evidence of what God has already done in one's life. You don't save yourself by abiding in God, you evaluate your life to gain assurance of your salvation if there is evidence that you are abiding in God. You also evaluate others to assure yourself of their salvation, or lack thereof.