One way to respond is to acknowledge that ALL religions use some pagan things. For example, the New Testament was originally written in the Greek language. The Greek language was a language of a pagan nation. Later on, Latin, the language of another pagan nation, became the official language of the Catholic Mass in the western parts of Europe. Catholics took the custom of statues of saints from pagans. But so what? Our statues are not of pagan gods. They are of Christ and Christian saints. Even the Jews translated their Bible into the Greek language (a pagan language) before the time of Christ. Even the English language is based mainly on a Germanic language (another pagan language). But the core the Catholic Faith can be clearly be seen to be Jewish and Christian. Jesus and his apostles all were Jews who practiced the Jewish religion. Christianity is a continuation of the Jewish religion. Islam used the crescent moon as a symbol. That’s from paganism. But Muslims do not worship the moon or a moon God. Just ask them. They’ll tell you they don’t.
Oh well, that’s one thought. There’s tons more about this on the Internet.
My understanding is that the origin of crucifixion dates back to ancient Egypt, well before the time of Christ. Is your friend referring to this type of Paganism, as opposed to the European Paganism we’re more familiar with? Although crucifixion occurred before Christianity, I cannot recall any lore of a resurrection. I would be curious to know!