In term of concept of God, neither Judaism nor Christianity closer to Islam. Both committed shirk, refer Qur'an:
And the Jews say: 'Uzair (Ezra) is the son of Allah, and the Christians say: Messiah is the son of Allah. That is a saying from their mouths. They imitate the saying of the disbelievers of old. Allah's Curse be on them, how they are deluded away from the truth! [At-Tawbah, 9:30]
However, among the followers of these 3 religions the Quran says Jews (and Mushrikins) show strongest enmity towards Islam but Christians are closer to Muslims:
Verily, you will find the strongest among men in enmity to the believers (Muslims) the Jews and those who are Al-Mushrikun (see V.2:105), and you will find the nearest in love to the believers (Muslims) those who say: "We are Christians." That is because amongst them are priests and monks, and they are not proud. [Al-Ma'idah, 5:82]
... if only they (the Christians):
And if only they had acted according to the Taurat (Torah), the Injeel (Gospel), and what has (now) been sent down to them from their Lord (the Quran), they would surely have gotten provision from above them and from underneath their feet. There are from among them people who are on the right course (i.e. they act on the revelation and believe in Prophet Muhammad SAW like 'Abdullah bin Salam), but many of them do evil deeds [Al-Ma'idah, 5:66]