For religious exemption, it doesn't matter if the cells are still there or if they got filtered out, or if they are used in the production process or just for development and testing. It also doesn't matter that these cell lines are from fetuses aborted in the 1970s and 1980s, it is the abortion itself that matters. So the first thing you want to know about a cell line is if it is abortion-derived, or a miscarriage, or derived from a cancer. And if the cell line is from humans (HEK293 is) or from monkeys.
Here is a (always up-to-date) table about the different c19 vaccines and the cell lines used (if any, some modern vaccines are created in a chemical process): https://lozierinstitute.org/update-covid-19-vaccine-candidates-and-abortion-derived-cell-lines/
Thanks, that linked to https://www.nature.com/articles/s41586-020-2608-y which states
The virus was rescued and propagated in T-Rex HEK293 cells (Invitrogen) in which antigen expression during virus propagation is repressed. Purification was carried out using CsCl gradient ultracentrifugation. Virus titres were determined by hexon immunostaining assay and viral particles were calculated on the basis of spectrophotometry16,17.
I don't really understand that beyond the spun it really fast to separate different parts out.
They use these cell lines because they have so much experience in creating variants of these cells. The cell lines used in virus isolation and production are modified in a way that they don't fight the virus, so the virus replicates fast. Because they know these cell lines so well, they then can sort out the virus by eliminating everything else.
(post is archived)