Because the author is a putz engaged in nonsense. Catholic belief is that salvation is through God's grace period, no if's and's or but's about it. Moreover the author knows this.
Active and Professing Christians said "accepting Christ as Savior and Lord" is the key to being a Christian (almost 9 in 10), while Liturgical, Private, and Cultural Christians favored more generally "believing in God" as the main element in being a Christian.
It does not say that Catholics are "Liturgical Christians", what is says is that most "Liturgical Christians" are Catholic and Lutheran. This is a poll and if Catholics didn't choose the answers you wanted then, you beef should be with other Catholics and not the author. Don't kill the messenger.
If you don't like the way the poll came out, change it, join the poll. NationalChristianPoll.com
Too many in this thread are confusing types of Christians with types of churches.