I fail to see why I cannot be both a faithful Catholic (or almost any other modern religion) and a scientist.
While indeed, you can be both and never run into any conflict, it's mostly the principles that are the issue here.
For a scientist, you need to be able to prove what you believe, and have good evidence for life around you and your beliefs on them. While in American court, the suspect is "innocent until proven guilty," in science, ideas are often "bullshit until backed up with evidence and case studies." This is good for many reasons, not the least because I don't want someone designing medicine, bridges, or what have you without completely understanding how they all work.
Pretty much all religions on the other hand, need you to take faith in God and his power, and in fact, sometimes questioning God's validity (which is the sort of thing a scientist needs to do everyday ((not just in God but in everything)) can be considered considerable offence, both to God and those who believe in Him. One of the most important characteristics of a Catholic (I was raised one) is faith, in God, in His son, and in the thousands of saints. This sort of belief often runs completely contradictory towards the scientific princibles, thus the reason why many people would say you can not be both.
Now, like I said earlier, you can be both fine, contrary to that picture you posted,
Einstein actually did believe in God, however his belief was much different than that of most Jews. Also, of course, there are many scientists who do not follow the "question everything" method, indeed if you did that to everything your life would most likely be very troubling. There are people on every range of the spectrum, from questioning everything (you'll know what this is if you have read
Stranger in a Strange land,) to people who do scientific jobs just following what their bosses tell them.
This is my view on how it can be troubling to be a strong Christian and scientist, but like I said, you can do both and feel fine, but I hope you understand what I said.