All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
In principle, it is not permissible for you to get married to this woman if she is, as you have stated in your question, without religion (atheist). Islam has legislated that it is not permissible for a Muslim man to marry a non-Muslim woman unless she is from the People of the Book and provided she is chaste. Allaah says (what means): {And do not marry Al-Mushrikat (idolatresses, etc.) till they believe.}[Quran 2:221] Indeed Allaah has clarified what is permissible for the Muslim nation as He Says (what means): {Lawful to you in marriage are chaste women from the believers and chaste women from those who were given the scripture before your time.} [Quran 5:5]
Therefore, we advise you to get married to a religious Muslim woman with good moral character who would be a comfort to your eyes and would help you in bringing up your children on Islamic religion.
Allaah Knows best.