Jesus raising Lazarus from the dead impacted a lot of people. The miracle increased faith in Jesus because it got people like Martha to rethink what Jesus could actually do. Mary anointed Jesus with valuable oil, likely out of thanks. But Jesus impacted even more people.
Eventually, a lot of the Judeans found out about the event not just because of what Jesus did, but also what happened to Lazarus. In fact, from 12:11, because of Lazarus, many of the Judeans believed in Jesus because they found out that Jesus can raise people from the dead.
However, the religious leaders also wanted to kill Lazarus because they found that Lazarus was part of the reason why many more people decided to believe in Jesus! From John 11:47-48, part of the motives involve keeping on to power, and the religious leaders feared that people turning to Jesus would result in them losing their status (even though Jesus is legitimately of great significance due to feats like raising someone from the dead).