Welcome to TripAdvisor.
What time does your flight arrive? Since it's a Friday, when public transport stops running in the late afternoon, you would probably need to take a taxi, which is by far the most convenient way anyway (obviously, at any time). You can see the cost here (spelled "Herzelya" on that page):
Taxis are always available, immediately outside the arrivals hall. The official dispatcher will put you into a taxi at the official rate and there is no need to tip the driver.
Even if you arrive early enough in the day to be able to take public transport, I wouldn't recommend it. There are trains from the airport to Herzliya, but you need to change in Tel Aviv, and the Herzliya railway station may be a very long way from where you want to go so you would need a taxi from there to your accommodation anyway.
Tour information for a Christian: more input needed from you. What denomination of Christianity? A Catholic tour is very different from an Evangelical one, and so on.
Please start a new thread asking about Christian tours, stating what denomination, how long for, whether you want a tour lasting a week or two, or just odd days here and there, any mobility difficulties, etc. You will get lots of answers.
Exactly where are you staying in Herzliya? If you arrive early enough you can take the train to Herzliya Station, then a short taxi ride to your accommodations.
I infer that you have already booked accommodations which implies that you will be touring on your own. How long is your stay in Israel? Will you rent a car? Are you mainly interested in Christian-related religious sites or do you want a more general tour? Etc, etc.
Thank you very much.