All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If this man utters the Two Testimonies of Faith (which is to say “Ash-hadu alla Ilaaha Illa Allaah Wa Ash-hadu Anna Muhammadan Rassoolu Allaah” (I testify that None has the right to be worshipped but Allah and I testify that Muhammad is the messenger of Allah), follows all the apparent rites of Islam, gives up the signs and symbols of disbelief, and it is strongly believed that he is sincere in his practice, then there is no harm in getting married to him.
We advise you to perform Istikhaarah prayer (to seek Allah's help and guidance) and consult your pious relatives or other Muslims before accepting his marriage proposal. Be careful in your matter; do not be a victim by those who pretend to be Muslims.
As for circumcision, it is not a compulsory condition for the validity of one's Islam.
For more benefit in this regard, please refer to Fataawa 84911 and 81632.
Allah knows best.