Make sure that they know that your way of worship is better than theirs, even if you both are the same Faith. Pre-Vatican II vs Post-Vatican II.....and anything in between.
If they don't pray the same way or as often as you do, make sure that your attitude shows that you know better than they do. *Everyone* knows that _______ and _______ are the ONLY ways to get to Heaven and you don't have time for those that don't know what you are talking about (everyone has heard of the Divine Mercy...you don't have time to explain it!!!!).
If you do something differently than the majority, it's because you are the only one who knows the truth of the matter; maybe someday your glory will be recognized.
Do not welcome or speak to others in pews around you.
If you are in a leadership position, don't return phone calls or emails to people with questions, especially when they are asking to get involved.
If others are dressed differently, or act differently, make sure they know either by looks or comments they are inappropriate.
Don't smile, make eye contact or shake their hands.
Act like you know a secret (a smirk is great), and if you tell them why, don't invite them to be a part of it. Always assume that if they were good enough, they'd already know about it and practice it.
If someone asks you a question, make the answer short and snappy, and act like they should already know the answer (whether it's where the restroom is, the priest's name, when Confession is, or how to join the Church). If you promise to help them later with something, make sure you don't!