Is it possible to convince an Atheist that God exists?
First, we need to know what you mean by the word God.
Second, no, it’s not possible to convince an Atheist that God exists. They’ll make ridiculous demands for objective physical evidence as though God, whatever it is, were necessarily a natural physical phenomenon like the rain, subject to measurement and manipulation.
Even if you were to accomplish this probably impossible feat very few Atheists would be convinced for exactly the same reason that you’re very unlikely to change anyone’s opinion about anything, especially when that person identifies with their position as a personal label and a large aspect of their identity, even with a great deal of passion and many years of arguing behind it. The situation becomes nearly impossible for the simple fact that Atheists are fighting in defense of the materialist, Science-centric worldview, which is the status-quo in our culture. The materialist Science-centric worldview is, you may notice, what we universally take for granted. Other things in our culture thus have to work around it. If they do not, they are shot down for interfering because our culture’s Science-centered perspective is so obviously correct to us, and correct specifically because it is “scientific,” that anything else, even regardless of evidence, becomes pseudoscience or, gasp, even the very scary, evil boogeyman called religion, an increasingly meaningless word which, to Atheists, seems to mean either “everything we don’t like” or “Christianity, Islam, and their nearest variants.” Often it means both. Notice that when an Atheist argues with a non-Muslim, non-Christian or anything remotely related, the Atheist will still argue at length as though that person were Christian. Atheists generally seem to know nothing of theology but memorized refutations to charactures of Christianity.
Atheists are hardly fighting for a cause, though they seem to be, but rather fight against threats to their established, One True Path — that is, the mythical “scientific method,” their singular certain path to Truth, or, as they say, the “closest approximation” to it, which is effectively indistinguishable from a claim to certain Truth for the purposes of this discussion. Shouting people down with, “This is the closest thing anyone may have to absolute, objective truth,” isn’t much different from saying to someone, “This is the absolute, objective truth.” In either case someone is attempting to force you to accept their view and not consider any other.
Some Atheists may eventually realize some of the flaws in their arguments and change on their own, but they probably will not change by being “convinced.”
However, the one sure way most Atheists would be “convinced” that God exists, whatever that even means, would be if the Scientific establishment were to say that it/he/she/whatever does exist. If the Scientific priesthood gives the Atheist permission and even commands it, as they would, most Atheists would follow suit and pretend that they’d never thought otherwise. Evidence, physical or otherwise, is not needed for this. The most compelling reason to be an Atheist, you see, is that it appears to be the intellectually progressive position; it is supposedly what the smart people say. It is what the “experts” say. To take a dissenting view is therefore to be at odds with the smart people, with whom the Atheist would like to be associated and whom they would emulate.
This last point is the most important point here. Atheist are generally only emulating who they perceive to be the smart people and they choose those people because they would like to be viewed by others in the same way they, themselves, view the smart people.
There’s more to be said here and I’ll get to it eventually, but was just a Quora answer that had gotten out of control. Instead of posting it there and opening myself to certain argument I am posting it here, on my own page, which is not frequented by Atheists, though they do seem to turn up like roaches any time the slightest disparaging thing is said of them.