Lets get down to the root of the matter, shall we? If we read Aquinas, we can't throw a stone without talking about virtue. In fact, he believed that there are four cardinal virtues: Prudence, Temperance, Justice, and Fortitude. In addition, there are three theological virtues: Faith, Hope, and Charity. These seven virtues would take books to unpack (look up the Summa sometime) and I'm not going to do that. I'd also have to end up finishing up my greek education...and I don't have the time. So here is a hugely watered down version of these virtues: (BTW @Desayjin, you went to a Jesuit school didn't you? You probably know a lot more about Aquinas than I, Ignatius had a soft spot for him, so feel free to correct me if I drive off the path.)
The Cardinal virtues are virtues that all men have access to, the theological virtues are virtues that are specific to Christ, and are possible through the indwelling of the Holy Spirit. This means that to a non-Christ follower, they can display and act through Cardinal Virtues, but only through a Christian, reflecting the very nature of God, can theological virtues be displayed. If you read the Bible, 1 Corinthians 13, Paul states "So faith, hope, and love remain, these three; but the greatest of these is love..." When Aquinas is talking about "Charity," This is what he means...sort of. Our English translations don't do the words agape or caritas justice. Love in the English language is a catch-all for many concepts: it could have romantic, sexual, familial, friendship, or even preferential undertones. Love means most often in our language: passion and feeling. This is not what Aquinas is talking about, nor is it what the Bible is referring to.
Caritas or "Charity" Is the concept of the infusion of the "Loving-kindness of God" in action coming from the very depth of the soul. Think about it as man being a mirror, shining a reflection of God...only much more powerful as that reflection has action to it. It is much more than a simple feeling. It is a Doing. It is Man AS God's hands. When Christians allow charity to motivate their actions, they display joy, peace, and mercy.It is my personal opinion that this is where people who share my Faith fail often. We are imperfect beings, shaped to perfection but bent by our own weight and as such do not reflect the perfect love of a creator who loved us so much that he sacrificed himself for us.
I started this post in a completely different vain. I wanted to talk about truth and how one cannot be tolerant and truthful without compromise. It's funny, but as I wrote it I realized that the question that I was asking was wrong. I think God spoke to me in that moment and made me as another question. I was asking "What is the purest truth?" and instead I needed to ask "What is the greatest virtue?" I still completely agree with the premise I was working on that truth exists and that it is a contradiction to hold two opposing worldviews with the same weight; but what can I do with that? Sure, I could beat a person over the head with the idea that their worldview is wrong, but my voice becomes a clashing cymbal.
I see so many Christians earning theology points, or trying to win philosophical or political arguments but the foundation of their motive is broken. We can have the greatest, most perfect argument, and yet fall under the weight of our own pretense because we aren't grounded properly in the the life-full, moving Grace of God. We could have written the most perfect, Word inspired treatise that is founded on sound doctrine...but still fall completely flat because it doesn't come from a place expressing the loving-kindness of God. We can have the perfect belief and go through the motions of our spiritual life but be dead because our hearts aren't being moved by the need to express the Word of God in his power. We can stand up for justice and the poor, and do all the programs at Church and go on the mission field...but if it comes from any other place than the inspired, willful, push of the Holy Spirit to work His will in the world...it is a empty gesture.
In the end, it doesn't matter if I know what the purest truth is...if I don't have 'God's so loved the world' at the center of my being...it doesn't matter.