I am not seeing a wide divide of conduct or conviction between those who attend a Christian church of whatever denomination on Sunday and their conduct in the world. As Gagafritz mentioned earlier, Christians are no more and no less 'sinners' than anybody else. "Sin" in this case is defined as that which harms ourselves and/or others and/or spoils the perfect creation that God gave us. We are all guilty by 'sins' of omission and commission and at times we all have feet of clay.
But though I know some self-proclaimed Atheists and agnostics who do participate from time to time, I simply don't see ongoing world relief ministries among some of the world's poorest people, or leper colonies, or thrift shops, or soup kitchens, or rehab centers, or homeless shelters, or blood banks, free clinics or hospital auxiliaries, etc. etc. etc. organized, staffed, funded, and maintained by Atheists and agnostics. These are mostly organized, funded, staffed, and operated by mostly Christians.
According to an exhaustive study headed by Arthur Brooks a few years ago, Christians, most especially those who attend church more regularly, are far more likely to contribute to chartieis, far more likely to volunteer, more likely to give blood, more likely to take risks to help others.
The anti-Christian and/or anti-religion crowd may likely focus on the occasional unethical, dishonest, and/or unprincipled person who identifies himself or herself as a Christian. Such people absolutely exist. They exist among Jews, Hindus, Buddhists, Muslims, and every other variety of religion and also among Atheists and agnostics too. They always have and always will.
But those on the inside track who see the big picture know that the Church and the Christians who make it up are absolutely making a difference in relieving suffering and giving a helping hand up and also in providing higher ethics in business and being a stabilizing and positive force in their respective communities - WHEN - Christianity is coupled with a free society.
I think it is no coincidence both in the USA and Mexico and elsewhere that as Christianity has been increasingly criticized and church attendance has declined, corruption and violence have escalated. You can point to no country in which Atheism is the official religious position and/or in which large segments of the population have not been oppressed and denied basic human rights.