Christianity in the roman empire.

[Jona Lendering]

Early Christians had no problem killing each other as they decided what was proper doctrine.

That's exaggerated. From the fourth century, I know two examples: Priscillian was executed by the emperor Magnus Maximus, but this had little to do with religion. The Spanish preacher had deduced from "blessed are the poor" that it was acceptable to steal from the rich. The other example is Nicholas of Myra striking and accidentally killing a heritic during the Council of Nicea; the story, however, may be inauthentic (Nicholas is not mentioned in the authentikon, the list of those present). Even if it is true, it should be noted that Nicholas was punished.

They had no problem pillaging pagan temples of anything of value.

That is correct. Christianity was a normal religion. It is to be regretted that the early Christians were not different from the Roman pagans government, who not only took the possessions of the adherents if Isis, "magians", Jews, Manichaeans, and Christians, but also sent them into exile or to the lions.

How many libraries were closed in Rome once Christians took over the city?

That's an old canard. The Christians took care of the libraries after they had, in the fourth century, recognized the value of ancient literature (think of Ambrose and Augustine). That so many ancient literature is now lost, has to do with the switch from papyrus to parchment; cf. this article on the disappearance of ancient texts. Note that Christian copiists took care of the poems of Martial, which they can not have appreciated, and of pagan books like Apuleius' Metamorphoses of Lucius.

http://www.religioustolerance.org/rel_pers2.htm

I think that is not a very good article, and you might have seen that for yourself: the author quotes the Wikipedia. Now the Wiki is fine when it discusses relatively value-free subjects like ancient bridge building - I love the contributions of our fellow-RAT Stephan - but when modern polemics are involved, the Wiki is to be avoided.

Note in that article the claim that pagans were religiously tolerant; have you ever read the Senatusconsultum de bacchanalibus? Many people were killed for their beliefs. Tacitus' tells about the persecution of Jews (exiled to Sardinia) and the adherents of Isis during the reign of Tiberius. Diocletian was merciless towards the Manichees. Et cetera.

I can sympathize with a site that calls itself religioustolerance.org; yet, I think it damages its own case when it presents arguments from the Wiki. It gives me the impression that it's tolerance for all, except for modern Christians. As it happens, I think that many bad things have been done in the name of Christianity, and I agree that criticism of certain tenets of Christianity is necessary, but I think that one's opinion about modern Christianity should not be projected upon Antiquity.