Your post is interesting. The Scripture you cite can more accurately be seen as exactly contrary to your exegesis.
People's love will grow cold because iniquity shall abound? Iniquity abounds, that is for sure. Iniquity abounding is the cause of the cold hearts, not visa versa.
The answer is the latter and the bible tells us when one sins it effects all of us. There is a connectivity in the church and the weight of what is going on is having grave effects
So then we can talk about the Chruch Greek Ek-klesia the out called of the called and their being an earthly carnal church the Klesia (The called) and that the true heavenly church is made up of the Ekklesia (the out called of the called) and say we can say: well this is not my arm or my foot (They are not my denomination, not part of the ministry I belong to or not my pastor) so I'm free and this has nothing to do with me.
But the ek-klesia is indeed a part of the the Klesia and is called to be light and salt to them -- so can we walk away and ignore this rising demonstratible tide of sin in the church that will wax worse and worse?