You're criticizing them for the wrong reasons. There's plenty of things to say about Christianity without going full retard Varg levels of petty.
Earnest biblical scholarship does wonders.
For example, the Christian doctrine on the nature of atonement is a radical deviation from the source material. The book of Hebrews (one of the Pauline letters that form the "constitution" of Christianity, so to speak), which tries to make the claim that Christ's death on the cross was the fulfillment of the sacrificial system, blatantly misquotes Pslam 40 when it says "When Christ came into the world, he said:
Sacrifice and offering you did not desire, but a body you have prepared for me", when Psalm 40:6 says "Sacrifice and offering You did not desire; my ears you have opened. Burnt offering and sin offering you did not require."
These mean two very different things. One insinuates that the sacrifice of Jesus was necessary for the atonement of sins, where the other is outright saying no such offering is necessary. "Ears being opened" means to obey, to turn to God. This view is seen elsewhere in the Tanakh like in 1 Samuel where we see that "....to obey is better than to sacrifice."
Judaism does not require sacrifices to gain forgiveness from God, only that one turn from their sinful ways and get back on the right path; whereas Christianity posits that man cannot do anything to merit his salvation, and that Jesus' sacrifice "covered" us by sating God's demand of justice.
In essence, the God of the Old Testament can be seen as far more forgiving than the God of the New Testament, as he asks for nothing but for you to turn back to him, no sacrifice necessary.
This example of misunderstanding (or differently interpreting) the Jewish side of the origins of Christianity is one of the many legitimate criticisms one could make. And it is way more convincing than "lol dead Jew on a stick."