Most Israeli Christians are Arab Christians (75%) or other non-Jewish immigrants. The Christian population is shrinking as a share of the population, it is below 2%. This is comparable to Palestine, where it is also estimated to be below 2%.
For example the mentioned Lebanon has a Christian population still about 35% which is more than some European countries. Yes, the whole region has a shrinking Christian population because of wars, conflicts, famines, humanitarian crisis, political radicalization and persecution.
Attacks on Christians in Israel from the "orthodox" Jews are growing.