Allah tells us about His servant and Messenger Lut, peace be upon him, and how he warned his people of Allah's punishment for committing an act of immorality which no human ever committed before them -- intercourse with males instead of females. This is a major sin, whereby men are satisfied with men and women are with women (i.e., homosexuality). Lut said:

أَتَأْتُونَ الْفَـحِشَةَ وَأَنتُمْ تُبْصِرُونَ

(Do you commit immoral sins while you see) meaning, `while you see one another, and you practice every kind of evil in your meetings.'

أَءِنَّكُمْ لَتَأْتُونَ الرِّجَالَ شَهْوَةً مِّن دُونِ النِّسَآءِ بَلْ أَنتُمْ قَوْمٌ تَجْهَلُونَ

(Do you practice your lusts on men instead of women Nay, but you are a people who behave senselessly.) means, `you do not know anything of what is natural or what is prescribed by Allah.' This is like the Ayah:

أَتَأْتُونَ الذُّكْرَانَ مِنَ الْعَـلَمِينَ - وَتَذَرُونَ مَا خَلَقَ لَكُمْ رَبُّكُمْ مِّنْ أَزْوَجِكُمْ بَلْ أَنتُمْ قَوْمٌ عَادُونَ

(Go you in unto the males of mankind, and leave those whom Allah has created for you to be your wives Nay, you are a trespassing people!) (26:165-166)

فَمَا كَانَ جَوَابَ قَوْمِهِ إِلاَّ أَن قَالُواْ أَخْرِجُواْ ءَالَ لُوطٍ مِّن قَرْيَتِكُمْ إِنَّهمْ أُنَاسٌ يَتَطَهَّرُونَ

(There was no other answer given by his people except that they said: "Drive out the family of Lut from your city. Verily, these are men who want to be clean and pure!") means, `they feel embarrassed because of the deeds you are doing, and because you approve of your actions, so expel them from among yourselves, for they are not fit to live among you in your city.' So, the people resolved to do that, and Allah destroyed them, and a similar end awaits the disbelievers. Allah says:

فَأَنجَيْنَـهُ وَأَهْلَهُ إِلاَّ امْرَأَتَهُ قَدَّرْنَـهَا مِنَ الْغَـبِرِينَ

(So, We saved him and his family, except his wife. We destined her to be of those who remained behind.) meaning, she was one of those who were destroyed, with her people, because she was a helper to what they did and she approved of their evil deeds. She told them about the guests of Lut so that they could come to them. She did not do the evil deeds herself, which was because of the honor of the Lut and not because of any honor on her part.

وَأَمْطَرْنَا عَلَيْهِمْ مَّطَرًا

(And We rained down on them a rain.) means; stones of Sijjil, in a well-arranged manner one after another. Marked from your Lord; and they are not ever far from the evildoers. Allah said:

فَسَآءَ مَطَرُ الْمُنذَرِينَ

(So, evil was the rain of those who were warned.) meaning, those against whom proof was established and whom the warning reached, but they went against the Messenger and denied him, and resolved to drive him out from among them.