One of the major reasons that he left must destroy history is to destroy the historical record of not just Christ himself, but of the myriad of ways in which modern culture itself would not be possible without Christianity, and where we are already in the process of returning now that we have largely abandoned this main thread of what allowed Western civilization to once flourish.
I'm not really going to encourage you to read through this if you are bothered by disturbing facts, but, the bottom line is that abortion and homosexuality are only part of the horrors of paganism that we have started to sample -- it DOES get worse, including infanticide, abandonment of children and rampant sexual abuse of children.
The illusion that "modern is better" is one of the saddest of the lies taught by "progressives". It is possible that the very elite of the left believes that an "inner circle" of erotic license is actually going to be "better" for them, but for the bulk of the population, pagan society is a dystopian hell of meaningless violence, hatred, hopeless debauchery and ugly early death. As Christianity rose, it gave the IMPRESSION of things improving only because Christianity is not only moral, but blessed. When we started turning from Christianity, Western civilization started declining, and the decline is getting steeper!
Good to at least be aware of the Christian Difference that is being destroyed so that "pleasure" can reign.
But really, Christianity's invention of children — that is, its invention of the cultural idea of children as treasured human beings — was really an outgrowth of its most stupendous and revolutionary idea: the radical equality, and the infinite value, of every single human being as a beloved child of God. If the God who made heaven and Earth chose to reveal himself, not as an emperor, but as a slave punished on the cross, then no one could claim higher dignity than anyone else on the basis of earthly status.
A deeper understanding of how Judaism and Christianity improved the lot of women and children is covered in the excellent column linked in this post -- it is also disturbing, but truth often is.