In context, Fr. Carrón said this on the morning of the first full day. Quoting Msgr. Giussani, he said, "Christianity is an event." He notes that those who belong to the Movement known as CL, the so-called cielini, this should have the ring familiarity. I'd even say that for many it has even perhaps become a cliché.
What does it mean to say that "Christianity is an event?" It is not enough, at least for one desirous of "living Christianity according to its true nature," Carrón insisted, to merely know the correct definition: "Christianity reveals itself, in its nature, in response to a present need."
If you do not recognize the persistence of your on-going need, then faith becomes empty, simply a matter of inculcated habit, which results in moralism, or sentiment- "I go to mass because it makes me feel good," or, "I go Mass because going helps me to be good, I learn good values." As Msgr. Giussani observed, "In Jesus' time, the problem was how to live, not who was right: this [latter] was the problem of the scribes and Pharisees."
The question that arises, at least for me, is, "Does it matter who is right?" I'd have to say, "Yes," but only insofar as being "right" helps me to solve the problem of how to live, assists me in realizing my destiny, to be happy. This is something I must verify in reality, not answer abstractly, as a theoretical problem. The criterion against which I measure happiness is my own heart.