@Allure To add to Peter Turner's comment, in Christianity what Jesus did is analogous to a suicide attack to deliver a death blow in a spiritual war against the devil, similar to Japanese kamikaze in WW II, with the anticipation of being glorified after death. It's an act of heroism, an act of love for the countrymen, which in Jesus's case, an act of salvation for humanity.

BUT as the Gospel of John presents it (I highly recommend the 2003 Gospel of John movie, found it in youtube for now), Jesus anticipated God the Father to glorify and resurrect Him after his death on the cross. Therefore, unlike the usual suicide (giving up on life because of depression, etc.) and unlike Kamikaze, it is not technically suicide, since resurrection is expected.