What happened is horrendous, but I don’t think it will end South Korean visits to The Holy Land. South Korean Christians are among the most committed. But I do think all groups should stay away from The Sinai Peninsula. Keep going to Israel. I have had fifteen trips there and feel safer within Israeli borders than anywhere else.
Why should an explosion in the Sinai, which is a part of Egypt, impact tourism in Israel? Just stay out of the Sinai and Egypt, or any country that is primarily Muzzie. Then you should be fine.