There were a lot to choose from:
1. God, the genocidal maniac, real estate developer who parceled out land to " Chosen Ones" and authorized the slaughter of the then present occupants of the land.
2. Rising from the dead and flying into the sky was right up there.
3. An Ark of insufficient capacity to hold 1/10th of the creatures known now to have been on earth (and, all of its other impossibilities).
But hands down for me, as a Catholic, and a teenager was the "Feast of the Holy Innocents" (as it was explained to me), celebrated to honor the child victims of Herod after Christ's birth - the Jewish males under 2-3 years of age because he, Herod, wanted to destroy the new King of the Jews. I thought: "couldn't God have waited a few years - he had all of eternity". That monstrous disregard of the well-being of Humanity (an exponential evil compared to Sandy Hook) struck even a street kid from the westside of Chicago as being beyond the bounds of contemplation. Imagine what a later surprise it was to discover Herod died before Christ was allegedly born ( I later discovered the calendar had been wrong), but the substance of my objection did not change. (This "story" meant to elevate, somehow, the importance of Christ's birth and power - appalled me and, literally drove me right out of the church). Since it was a story I remember from 59 years ago, and before I manage to destroy all my credibility on issues - I will research after this post, so please forgive me any error because I don't want to re-type this entire posting.