If what Saul of Tarsus did pre-conversion can be attributed to the devil, then the "devil made me do it" excuse starts to carry weight.
But if we can imagine that even murder is a work of the flesh, suddenly, how horribly humans can be WITHOUT a devil, terrifies. That is too much for some.
However, he that sinneth is of the devil, as
1 John 3 reads, and so, since Saul was definitely in sin, I suppose an argument could be made...though not enough to convince anyone that Saul was possessed; rather, that Saul, in the flesh, was subject to the wiles of the devil, just like anyone else who isn't regenerated from above.