Agnostics and atheists share the lack of beliefs in gods. The Agnostic starts from the fact that the evidence neither supports the existence of god/gods nor proves that god/gods do not exist (how do you prove a negative?). Lacking the evidence, the Agnostic refuses to believe in a god, leaving the issue open. In any case, the Agnostics act the same as Atheists, that is, as there is no god to inform their actions.
The Atheist, says the same thing that the Agnostic, but take the factual approach that there is no god, that is, there is no open issue. Otherwise, there is no difference in how Atheists and Agnostics act in the Universe.
No religion can provide positive evidence of its truthfulness, therefore all it is based in the capacity of the individual for being hoodwinked by a deceiving preacher.
The notorious utterance of the Biblical adept stating that "by their works you will know them" is consistently applied to evidence of wrongdoing by the "others", either believers of another religion or non-believers as a class. When a wrongdoing by a follower of the promoted religion might be supported by the proper evidence, the immediate claim is to distance from the believer as "a lost soul" implying that the believer's action doesn't disprove the religion, in the process destroying the logic of the original "by their works you will know them".
The Atheist doesn't start from a religion, rather the Atheist is the one who had arrived to Atheism. All the roads take you to NO GOD.
What kind of Atheist will an individual be, cannot be defined by the single non-belief in god/gods, nor the past of that individual. The quality of the human character exhibited by the Atheist will provide the answer. It all will depend in how are we committed to the "golden rule" regarding the Universe and our fellow travelers.
Actually there is a difference in the social acceptance of Agnostics as opposed to Atheists, advising many an Atheist to tone it down and profess Agnosticism from the lips out.