It is not for Idolators to maintain the Masjids of Allah

Allah says that it is not fitting that those who associate others with Allah in worship should maintain the Masjids of Allah that were built in His Name alone without partners. Those who read the Ayah, "Masjid Allah", said that it refers to Al-Masjid Al-Haram, the most honored Masjid on the earth, which was built, from the first day, for the purpose of worshipping Allah alone without partners. It was built by Khalil Ar-Rahman (the Prophet Ibrahim) peace be upon him. The idolators do this while they themselves testify to their disbelief with their statements and actions. As-Suddi said, "If you ask a Christian, `What is your religion', He will tell you he is a Christian. If you ask a Jew about his religion, he will say he is a Jew, and the same for a Sabi' and a Mushrik!"'

أُوْلَـئِكَ حَبِطَتْ أَعْمَـلُهُمْ

Verse 17 was describing the negative aspect as related to the Mushriks. It said that they did not deserve the honor of building and maintaining mosques. Verse 18 takes up the positive aspect relating to mosques by saying:

إِنَّمَا يَعْمُرُ‌ مَسَاجِدَ اللَّـهِ مَنْ آمَنَ بِاللَّـهِ وَالْيَوْمِ الْآخِرِ‌ وَأَقَامَ الصَّلَاةَ وَآتَى الزَّكَاةَ وَلَمْ يَخْشَ إِلَّا اللَّـهَ ۖ فَعَسَىٰ أُولَـٰئِكَ أَن يَكُونُوا مِنَ الْمُهْتَدِينَ ﴿18﴾