But observe what he alleges as a proof of his statement: “Christians at first were few in number, and held the same opinions; but when they grew to be a great multitude, they were divided and separated, each wishing to have his own individual party: for this was their object from the beginning.” That Christians at first were few in number, in comparison with the multitudes who subsequently became Christian, is undoubted; and yet, all things considered, they were not so very few. For what stirred up the envy of the Jews against Jesus, and aroused them to conspire against Him, was the great number of those who followed Him into the wilderness—five thousand men on one occasion, and four thousand on another, having attended Him there, without including the women and children.
For such was the charm of Jesus' words, that not only were men willing to follow Him to the wilderness, but women also, forgetting the weakness of their sex and a regard for outward propriety in thus following their Teacher into desert places. Children, too, who are altogether unaffected by such emotions, either following their parents, or perhaps attracted also by His divinity, in order that it might be implanted within them, became His followers along with their parents. But let it be granted that Christians were few in number at the beginning, how does that help to prove that Christians would be unwilling to make all men believe the doctrine of the Gospel?
Source: Against Celsus (New Advent)