Be very diligent in your Torah learning. Know that when you learn Torah, you’re growing yourself also with the ability to answer any heretic. There are many people out there who challenge the fundamentals and principles on which the Torah is based. Only somebody who is a well-rounded Talmid Chacham (Torah scholar), with knowledge in all areas of Torah, could answer them and have answers to all the attacks they may make on Torah.
So know a lot of Torah, and know that you’re serving a real purpose by answering these people who are trying to fight the principles of Torah. When a person recognizes that, he’ll fight with all his might, because if these beliefs out there go unanswered, they could spread, and eventually people, especially among the masses, will take them in and start believing in them. So you have to know that you’re fighting these heretical beliefs.
And know before whom you’re working. You’re working before HaKadosh Baruch Hu (the Holy One, Blessed is He). When you’re dealing with these heretics and hearing so much of their garbage and so much of their misinformation about the beliefs of the Torah, it could eventually have an effect on you. You want to be very careful that these ideas don’t enter your mind.
So know that you’re working before Hashem, the all-powerful God, who knows everything, who knows every thought. Be very careful and very diligent not to allow their thoughts to enter your brain. And know that your employer, obviously Hashem, is reliable. You can rely on him to pay the wages for your work. You’re putting a lot of effort and risk into fighting these heretics, but know that it’s worthwhile. Hashem will take care of you. You’ll receive a tremendous reward if you carry out this work and fight the beliefs that are against you.