The suggestion that the Resurrection is the ONLY sign we need is supported neither by Scripture NOR the Catechism of the Catholic Church.
The reason neither support this suggestion is that the suggestion is false.
It’s just another strawman argument.
If its ONLY the Resurrection, then why do the Calvinists have “TULIP”? For that matter, where is “TULIP” in the Bible because if it’s not manmade I don’t know what is.