The reason why the one to whom a homosexual act is done is to be executed
Question

                Why is the one to whom a homosexual act is done to be executed like the one who does it?.
Praise be to Allah.Al-Tirmidhi 
    (1456), Abu Dawood (4462) and Ibn Maajah (2561) narrated that Ibn ‘Abbaas 
    (may Allaah be pleased with him) said: The Messenger of Allaah  (peace 
    and blessings of Allaah be upon him) said: “Whoever you find doing the 
    action of the people of Loot, execute the one who does it and the one to 
    whom it is done.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. 
The Sahaabah 
    were unanimously agreed on the executing of homosexuals, but they differed 
    as to how they were to be executed. 
Some of 
    them, such as Abu Bakr al-Siddeeq and ‘Ali ibn Abi Taalib (may Allaah be 
    pleased with them) thought that they should be burned to death. Some of 
    them, such as Ibn ‘Abbaas (may Allaah be pleased with him) thought that they 
    should be thrown from a tall building followed by stoning. Some of them 
    thought that they should be stoned to death, which was narrated from both 
    ‘Ali and Ibn ‘Abbaas (may Allaah be pleased with them). 
See: 
    al-Mughni (9/58). 
The reason 
    why the one to whom such an act is done should also be executed is because 
    he is a partner in the sin, because this sin can only be committed if both 
    parties take part, so it is only just to carry out the punishment on both of 
    them. Similarly in the case of zina (adultery), the punishment is carried 
    out on both the man and the woman. Moreover there is nothing good to be 
    gained from letting the one to whom it has been done remain alive, because 
    of the great evil that has befallen him and because of the great evil that 
    may result from his presence. 
It says in
    Mataalib Ooli al-Nuha (6/174): Even though adultery and homosexuality 
    are both immoral deeds and are both evils that go against the wisdom of 
    Allaah in His creation and His command, in homosexuality there are 
    innumerable evils and it is better for the one to whom it was done to be 
    executed than to let him repeat that evil action, because he has been 
    corrupted in such a way that there is no hope of reform for him, and there 
    is no goodness left in him, and after that he will not feel shy before 
    Allaah or before His creation. The sperm of the one who did that will affect 
    his heart and soul as poison affects the body, and he does not deserve to be 
    guided to anything good, and every time he tries to do something good, 
    something will happen to spoil his good deed, as a punishment to him. Hardly 
    ever do you see one who was like that in his youth but he is the worst he 
    can be when he grows old. He does not gain any beneficial knowledge or do 
    any righteous deeds, or repent sincerely, in most cases. Once this is 
    established, the evil consequences of homosexuality are among the worst of 
    evil consequences, so its punishment is one of the most severe of 
    punishments in this world and in the Hereafter. 
The 
    companions of the Messenger of Allaah  (peace and blessings of Allaah be 
    upon him) agreed unanimously that the homosexual is to be executed, and none 
    of them differed concerning that. Rather they differed as to the method of 
    execution. Some people thought that this difference means that they 
    disagreed about executing him, so they narrated it as a matter concerning 
    which the Sahaabah differed, but it is a matter concerning which there was 
    consensus among them, not a matter of difference. End quote. 
The source 
    for this was Ibn al-Qayyim (may Allaah have mercy on him), who mentioned it 
    in al-Jawaab al-Kaafi li man sa’ala ‘an al-Dawa’ al-Shaafi. 
But if the 
    one to whom it was done was forced, then he is not to be punished, because 
    the Prophet  (peace and blessings of Allaah be upon him) said: “Allaah 
    has forgiven my ummah for mistakes and forgetfulness, and what they are 
    forced to do.” Narrated by Ibn Maajah (2045); classed as saheeh by 
    al-Albaani in Saheeh Ibn Maajah. 
See also the 
    answer to question no. 38622 
    for more information.
And Allaah knows 
    best.