One trouble I have accepting Christianity as truth-based is the stark differences between the God of the Old Testament and the God of the New Testament. These differences seem peculiar to me. I would not have imagined an omniscient God would experience dramatic shifts in expressed personality over a span of a mere few thousand years. Our human personalities evolve greatly over our short lifespans because we acquire knowledge, we come to understand that knowledge, and we struggle with hormonal fluctuations that accompany the delicate process of growing and dying. God would have seemed immune to those issues, being both omniscient and omnipotent. And yet He seems to change.
This Old Testament God did a lot of punishing. For their disobedience Adam & Eve were cast out of Eden with all of us now suffering decay and death as a result. For man's growing wickedness all but Noah and his kin were killed in the flood. For their impenitent sin, everyone in Sodom and Gomorrah was killed except Lot and his two daughters. And for their enslavement of the Jews, all the first born males in Egypt were killed. And beyond all the punishment there is an awful lot of testing of men, including the horrible tale of Job and Abraham's near sacrifice of Isaac. And there are ever so many rules laid down in the Old Testament about the behavior we adherents are required to keep lest be kept out of heaven or deserve to be stoned to death. And of course there is the curious fact that Old Testament God is not described as a trinity.
The New Testament God is markedly different. God does not engage in widespread punishment, does not kill those who transgress upon Him or His son, Jesus. And God seems little interested in testing people's faith, except perhaps that of His son. And the New Testament seems to relay a doctrine primarily about love, tolerance, and the need to focus on the core Biblical principles (e.g., love thy neighbor) and less on the minutiae (e.g., don't eat shellfish). And somewhat surprisingly, God also revealed Himself to be a trinity, Father, Son, and Holy Spirit.
How can these two very different experiences of God be reconciled, without either admitting God Himself radically changed over a period of a few thousand years, or if God is the same then admitting that man's account of God must be wildly inaccurate? Both possibilities strongly discourage my belief.