One of the most frustrating things in Christianity is the perception of the "One, True Church"TM. I'm almost certain some one's trademarked that phrase given how many people claim to be the true faith. Any student of church history realizes the excessive amount of politics, egos, and posturing that goes into the various schisms and breaks throughout Christianity. Each church then claims to be the true church, the on that is the only successor. True, I think the Church Catholic is the proper church, but I likely lump many, many more traditions and people into that category than my exclusionary brethren.
Equally repugnant is when a person joins a new church and presents the image that he/she has now joined the One, True Church. This often follows with proclamations that the previous church in which they served is invalid, worthless, etc. That is unfair to the People of God who received the sacraments from that person or depended upon them for their spiritual well being. One cannot erase their history, and I think it is important to emphasize that a change in denomination is a personal journey. It does not nullify all the actions of the past and it is certainly not desirable to vilify the previous group to which one belonged. Yet, this has happened all too often when Anglicans become Catholics, or Catholics become Orthodox, or Orthodox become Catholics, etc., etc., etc. We shift and grow throughout our faith life and sometimes we come to the realization that we are no longer called to our current tradition. Let us, then, depart as friends without bitterness and anger.
A fool gives full vent to his anger, but a wise man keeps himself under control. - Proverbs 29:1.