And Newman's attack on Pope Pius IX's "Syllabus of Errors" is the final nail in his non-sainthood coffin.
I looked for validation to confirm your charge against Blessed Cardinal Newman and found that the truth is the OPPOSITE:
Newman came into direct confrontation with Modernism
, which was known as Liberalism in his time. His writings against this "sum of all heresies," as Pope St. Pius X put it
, condemned in Pope Pius IX's Syllabus of Errors
, are clear and prescient. He saw in the middle of the 19th century that the Church would be submerged in this heresy, as indeed she is in this Vatican II period.
Here is Newman's description of the errors of Liberalism (Modernism), delivered in his bigletto speech of 1879, when he received the cardinal's hat. As you read it, reflect upon how his words describe exactly the environment that has taken over the world today, 125 years later:
To one great mischief I have from the first opposed myself. For thirty, forty, fifty years, I have resisted to the best of my power the spirit of liberalism in religion. Never did Holy Church need champions against it more sorely than now, when, alas, it is an error overspreading as a snare the whole earth.
Liberalism in religion is the doctrine that there is no positive truth in religion, but that one creed is as good as another, and this is the teaching which is gaining substance and force daily. It is inconsistent with any recognition of religion as true. It teaches that all are to be tolerated, for all are matters of opinion. Revealed religion is not a truth, but a sentiment and a taste; not an objective fact, not miraculous; and it is the right of each individual to make it say just what strikes his fancy.