Praying in a corrupt Masjid
How can one go into a Masjid these days when all of the mosques have the word Allah and Muhammad side by side stencilled or in carvings mounted on the walls?
Surely, if one goes into these Masjids knowing the truth, one cannot then ignore what is right in front of oneself. Would this not also be a form of Shirk as you would then be denying the command not to associate any name with Allah? I like to go to the masjid to worship Allah alone, and to glorify Allah alone, but I am always faced with an Imam whose every second word is in glorification of Muhammad or his companions!
Is it acceptable to make Salaat at home, so as not to be exposed to this?
As the Quran is the true word of God, we expect to find all our answers in the book, and the answer to your question is also given in the book.
The Quran makes it very clear that all masajid are for commemorating the name of God alone (not Allah and Muhammad!). Moreover, all the words of our salat (prayer) should be dedicated to the name of God alone:
"The masajid (places of worship) are for the name of God alone; do not call on anyone else beside God" 72:18
"Say, "My Contact Prayers (Salat), my worship practices, my life and my death, are all devoted absolutely to GOD alone, the Lord of the universe" 6:162
"He has no partner. This is what I am commanded to believe, and I am the first to submit." 6:163
"I am God; there is no other god beside Me. You shall worship Me alone, and observe the Contact Prayers (Salat) to commemorate Me alone." 20:14
Believers are commanded not to enter or pray in any masjid that harbours idol worship (shirk). If we cannot find a masjid that is dedicated to worshipping God alone and dedicated to commemorating His name alone in the salat, then we are advised to pray at home or with any group of genuine believers.
Besides, a masjid is anywhere where there is prostration, so in theory, if we are praying with others in our home, or any other place, that place becomes our masjid.
Here are the relevant Quranic words:
[9:107] There are those who abuse the masjid by practicing idol worship, dividing the believers, and providing comfort to those who oppose God and His messenger. They solemnly swear: "Our intentions are honorable!" God bears witness that they are liars.
[9:108] You shall never pray in such a masjid. A masjid that is established on the basis of righteousness from the first day is more worthy of your praying therein. In it, there are people who love to be purified. God loves those who purify themselves.