Part of the doctrine of most branches of evangelical Christianity is that it is important to convert others to the belief in order to save their eternal souls. This involves influencing others in order to sell the system.
If you want to sell an idea to someone it helps to know your audience. Going into a discussion with a set of false notions about the beliefs and values of those you are talking to just makes you sound ridiculous. You need to understand what the real issues are, not just the ones you would like to think are the real issues.
You will make no headway with convinced atheists, especially if they are ex-Christian, if you insist that atheists are less moral than Christians, that all moral values come from the Jewish or Christian god (Yahweh and Jesus, respectively) or that moral values are absolute and unchanging.
Let’s take the assumption of unchanging moral codes first.
When I was a young woman it was solely Catholics who were steadfastly against abortion. Protestants were generally not. These days the fundamentalist streams of Protestant Christianity have forgotten this past and now identify with the Catholics.
Similarly, divorce was viewed as deeply immoral by all Christian groups. Protestant Christian ministers who married divorced people lost their jobs. An English Prince lost a throne and lived in exile in order to marry an American divorcee. An English Princess was forbidden to marry the man she loved because he was divorced. Children like me were forced to live in loveless and violent marriages because our church decreed that we did and the laws of the nation made it very difficult for parents to get a divorce. Times have changed. These days American Baptists have a massive divorce rate which is way greater than the rate for atheists. What is more, the more religious the person, the greater their risk of divorce.
Now let’s look at the charge that atheists have no moral code and are therefore more immoral than Christians.
Multiple reputable studies have shown that the countries with the lowest rates of abortion, illegitimate births and teen pregnancies are those countries with the lowest percentage of people who believe in a god or other supernatural beings.
Similarly crime rates and prison populations are also lowest in the relatively godless countries.
The US is an outlier. It is the most Christian of the industrialized countries and also has the highest crime rates, the highest abortion rates, the largest prison population and the highest divorce rates. Even within this nation, these rates are highest in the Bible Belt States and lowest in areas where the religious right are less prevalent.
Countries like Africa which have rising rates of evangelical Christians have rising Christian-based slaughter and torture rates along with it. Bishops of these primitive churches take the KJV Bible literally. They believe that Christians “should not suffer a witch to live” and that they are being “led by the Spirit into all truth” when they determine which child is, or is not, a witch. Child poisonings and witch burnings have now become part of the Christian culture on this continent. Other evangelical clergy in Africa have been intimately involved in wholesale massacres. There are no such mass slaughters in the name of “righteousness” by the non-believers of these countries.
Which brings me to several other points which you may have wrong.
Convinced atheists (that is, those who have arrived at this position as the result of prolonged and careful thought and study) do not choose atheism because it allows them to carry on an immoral life-style. In fact, the majority of atheists did not choose to become atheists at all. It simply creeps up on them. That is why they talk about losing their beliefs instead of choosing them.
You may, however, find a superficially similar position to the evangelical presumption among young people. This group may choose a default-style atheism as a rebellion against their parents, the authority of the community and the religion of their childhood. It can feature hard swearing, hard drinking, reckless gambling, irresponsible sex, social rudeness, drug experimentation and a host of other dangerous and defiant activities. For a number of people this is an unfortunate part of growing up and finding one’s own identity.
Most youths find their way out of this phase before they hit 25. A few end up harming themselves and others before being faced with a “crunch-time” experience. The crunch-time sub-group is a lucrative mine for religious conversions and re-conversions to faiths which impose a moral code as part of group acceptance. Others end up in the rooms of psychiatrists, psychologists, social workers, welfare officers, law enforcement and corrections personnel.
Of course, some people never outgrow this stage of development. A few engage in criminal activity; most do not. These are the people who think that “freedom” involves using foul language at every opportunity and who reject the good of the many in favor of the belief that it is their inalienable right to act only in the interests of themselves and those they choose to care for. This may eventually become a thought-out position but is not representative of the position of the majority of mature atheists.
Convinced atheists do not choose to reject god. They simply find that they can no longer logically, and in good conscience, support such a belief. It is a matter of intellectual integrity. Former beliefs are usually relinquished reluctantly and often with considerable pain.
Convinced atheists do not hate god. You cannot hate something which you have finally conceded is extremely unlikely to exist and, if it does, almost certainly does not exist in any of the forms attested to by one or more of the vast array of Christian sects, denominations, congregations, schools of thought and personal revelations. Children who lose their belief in Santa do not hate Santa. The ones who hate this mythical figure (for not bringing them the toy they wanted) are the ones who believe he exists.
Convinced atheists are rarely atheists purely because they lack knowledge of Christianity, the fellowship of “real” Christians or an experience of a relationship with Jesus. A large number of atheists have a better understanding of the Bible than the average Christian and many trump the knowledge of the average evangelical preacher as well. There is a sizeable proportion of newly vocal atheists who have theological training, have run Christian ministries or have taught in institutions which train clergy. Some are still working as ministers or teaching theology because this is the only marketable skill which they possess and/or they do not have the financial or emotional resources to start over in a new industry. Others continue in this double life because they cannot conceive of a way to come out of the closet without significantly harming their immediate family, whether as the result of poverty, forced relocation or hate crimes and persistent bothering by continuing Christians. Theirs is a very difficult and precarious situation. You would be surprised just how many people like this there are.
Convinced atheists do not have lives which are devoid of meaning and purpose. Life is what they make it. It is precious because it is the only one they have.
Finally, convinced atheists come in many packages and have a wide variety of viewpoints, moral positions, political affiliations and ideological leanings. A few are communists; most are not. Some are nihilists (Nietzsche); most are not. Some are libertarians; most are not. Many are humanists; some are not. Many are liberal; some are not. Most are “pro-choice”, a few are not. Many are highly educated; many are not.
When you can understand and accept all this then, and only then, will you be ready to talk to an atheist and have him or her take you seriously. Until then you are trying to convince and converse with people who don’t actually exist.