The Pharisees did believe in life after death. When Paul had to appear in the Temple to answer charges the priests brought against him, he tossed in the question of life after death. This got the Pharisees on his side, which derailed their proceeding.
Each Gospel describes Jesus predicting his return from the dead – so odd a claim that no disciple understood it until after the fact. Subsequent lore details the remaining eleven apostles’ appalling deaths; only John survived to old age, and he died in captivity with no company other than Roman guards. No disciple considered recanting his story.
Paul Kalman’s answer points out that Jesus’ statement, “GOD is a GOD of the living not of the dead,” reinforces the idea of souls surviving bodily death.
A few days before His crucifixion Jesus told the high priests that Abraham had seen Jesus’s coming and was glad, and further that “Before Abraham was, I AM.”
To argue against the literal resurrection requires one to deny the entire Christian Scripture and its teachings.