The Lord told his disciples a number of times to love one another, or in a better translation keep on loving one another, as He loved them (John 13:34). Every believer is also a disciple of His, and we are to love each other as He has loved us! This love does not come naturally or there would be no need for the commandment: it requires effort, perseverance and a will to obey our Master, and can only be attained with the power of the Spirit of God.
Obedience to Christ's commands is a prerequisite to discipleship and service: He was the disciples' Rabbi (chapter 1:38; 13:13) and Lord (chapter 13:13). The Christian life involves following Christ's instructions, in order to bear fruit. He laid down His life for us, proving that He was the greatest friend we could ever have. He doesn't require all of us to die for Him to prove our own friendship, but we prove it by our obedience to Him as Lord, by continuously keeping His commandments. Abraham was likewise called the Friend of God because of his faith and obedience (James 2:21-23). A progressive intimacy is observed: servants (chapter 13:13), friends (chapter 15:15), brothers (chapter 20:17).
We are His servants, because we have acknowledged Him as our Lord and Master, and owe him our unqualified obedience. Because of our obedience, He calls us His friends, and, like the LORD searched out Abraham to reveal His plan to him because Abraham was His friend, the Lord Jesus has revealed the things of God to us. That is what a friend does. He calls us His brothers because in a human sense His Father is our Father (by adoption) and we are coheirs to His kingdom.
One night His disciples had been guilty of jealousy and wrangling (Luke 22:24; John 13:5,15), so He repeated the commandment that they love one another, for the third time. This should be the relationship of believers.
As to relationship with the world, like the disciples, a believer in Christ Jesus will be hated (unloved) by the world. A Christian's popularity, or lack of it, can be an indication of how he is representing Christ to the world. No Christian has any right to be more popular than the Lord Jesus was, so we should just keep giving out the Word and beware of a compromising position in order to be popular.
The world will not love a follower of the Lord Jesus, and that doesn't mean to act oddly or to be super pious: the very existence of believers is a reproach to the sinful world (John 7:7; 17:14; 1 John 3:13). Even in local churches there are folk who are not honestly born-again, and they will hate the preacher if he is true to the Word of God.
Beware of those who are popular with the world. The world does not know the Father, and does not want its sins revealed. The Lord Jesus exposes evil, like a light turned on where before was darkness, and the world hates the one who turns on the light.
The world does not hate their idea of God, some vague Someone out yonder. It is Christ they hate, and when a man hates Him, he is hating God the Father also. We can still be popular if we only say we believe in God. The real test is our relationship and attitude toward Jesus Christ and our witness of Him. We cannot be popular and believe in the Lord Jesus Christ, because He is the One who is hated.
The "world" and the ecclesiastics (Sanhedrin) had united in an attitude of hostility to Christ and in reality to God, thereby sinning because the Lord Jesus had not only come and spoken to them, but also done among them the works which no one else did, proving that He was the Messiah. The Lord Jesus identified this hostility with fulfilment of Psalm 35:19 and Psalm 69:4 when He said they hated Him without a cause. They hated Him because they had created a false god who was not the God of the Scriptures. It has been said, "God created man in His image and now man is creating a god in his image." That is the kind of god the world wants today and the kind of god they think is running the universe.
The Lord Jesus referred again to the Holy Spirit, who proceeds from Him and from the Father, as the Helper. He is the Spirit of Truth, and his mission is to testify of Christ, as it should be ours. The Lord told the disciples that they would bear witness of Him because they had been with Him from the beginning: this was the reason why they were called to be his Apostles, at the beginning of His ministry (Luke 6:13). The Gospel of John is the witness given by this Apostle, and it could only be given by someone who, like him, had been with the Lord Jesus from the beginning. The Holy Spirit still bears testimony concerning Christ, and makes the Lord Jesus real to us. A sure way to tell whether the Spirit of God is working is whether Christ is being glorified.
The Lord didn't want the apostles to be upset (to stumble) at what was going to happen to them. It is the practice of founders of organisations, and especially of religions, to attempt to present a glorious future for their organisations. The method of the world is to build up the wonderful benefits and to play down the hardships and disadvantages and privations and sacrifices. How different our Lord is! Earlier on (chapter 14) He had told His disciples that He was going to prepare a place for them and that He would receive them unto Himself, but now He made it very clear that they would be ostracised by their society - to be put out of the synagogues would make them social outcasts in Judea. The injustice towards them would be such that people would think they were doing God a service by murdering them! And this would happen because they (the Jewish leaders and their followers) had not known the Father or the Lord Jesus, for the Messiah whom He was.
Likewise, if we are going to follow Him we must forsake ourselves, and take up our cross (not His) of enmity and persecution. If we suffer with Him now, we shall reign with Him when He sets up His kingdom. He said His followers are going to be in the world but not of the world and that the world will hate them. He never said they would have an easy time, or that they would convert the world.
Many try to popularise the Christian "religion" and make it attractive to the world, using all kinds of devices. They say, "We have to do this to win the world." Who told them they were going to win the world? If we stand for the Word of God, we will find that the world won't love us, and will experience the hatred that Christ experienced. The world hates the Word of God because, like in the times of the apostles, it does not know God and rejects the Lord Jesus as His Son.
The Lord Jesus was letting His disciples know what was coming and He was training them so that they would be prepared for it. The Lord always trains and prepares us for that which lies ahead. If we want to serve Him well, let us be warned of the trouble ahead and be ready for when it comes.
Also see:
Chapter 15
12 "This is My commandment, that you love one another as I have loved you.
13 "Greater love has no one than this, than to lay down one's life for his friends.
14 "You are My friends if you do whatever I command you.
15 "No longer do I call you servants, for a servant does not know what his master is doing; but I have called you friends, for all things that I heard from My Father I have made known to you.
16 "You did not choose Me, but I chose you and appointed you that you should go and bear fruit, and that your fruit should remain, that whatever you ask the Father in My name He may give you.
17 "These things I command you, that you love one another.
18 "If the world hates you, you know that it hated Me before it hated you.
19 "If you were of the world, the world would love its own. Yet because you are not of the world, but I chose you out of the world, therefore the world hates you.
20 "Remember the word that I said to you, 'A servant is not greater than his master.' If they persecuted Me, they will also persecute you. If they kept My word, they will keep yours also.
21 "But all these things they will do to you for My name's sake, because they do not know Him who sent Me.
22 "If I had not come and spoken to them, they would have no sin, but now they have no excuse for their sin.
23 "He who hates Me hates My Father also.
24 "If I had not done among them the works which no one else did, they would have no sin; but now they have seen and also hated both Me and My Father.
25 "But this happened that the word might be fulfilled which is written in their law, 'They hated Me without a cause.
26 "But when the Helper comes, whom I shall send to you from the Father, the Spirit of truth who proceeds from the Father, He will testify of Me.
27 "And you also will bear witness, because you have been with Me from the beginning.
Chapter 16
1 "These things I have spoken to you, that you should not be made to stumble.
2 "They will put you out of the synagogues; yes, the time is coming that whoever kills you will think that he offers God service.
3 "And these things they will do to you because they have not known the Father nor Me.
4 "But these things I have told you, that when the time comes, you may remember that I told you of them. And these things I did not say to you at the beginning, because I was with you.
ohn 15:12-27, 16:1-4 (NKJV)