As far as I know, the State of Israel has only a few minor restrictions on the activity of missionaries, such as a law against offering monetary incentives to people to convert. Whatever restrictions there are, are not really enforced in any case. Missionary activity is going strong there, especially by the sects Messianic Jews and J Witnesses.

In your question, you did not use the word "missionary" but rather you phrased it as "Christians teaching their faith to non-Christians" which could mean when the non-Christians come on their own initiative and wish to learn about Christianity. In that case, there are certainly no laws against that.

As Torah Jews, we of course reject Christianity and consider it a form of idolatry. We reject the notions that 1) the messiah could come and then die without redeeming the world 2) the messiah could be anything more than human, or be an object of worship 3) the messiah could abrogate the laws of the Torah.

We are against the State of Israel and we hold that Jews during exile have no right to rule over non-Jews and restrict them from their free speech. At the same time, we support the activities of private anti-missionary groups (like Yad L'achim in the State of Israel) who educate ignorant Jews so that they do not fall prey to the missionaries, as well as bring back Jews who have already joined the missionary sects. We hold that this activism is good as long as it is carried on by non-government bodies.

I hope this information answers your questions.