A Christian funeral is done not only to say “goodbye” the the believer, bring confort to those who are left behind, and also to celibrate the life of that person.
Catechism of the Catholic Church (no. 1032): prayer for the dead is one of the spiritual works of mercy.
1032 This teaching is also based on the practice of prayer for the dead, already mentioned in Sacred Scripture: “Therefore [Judas Maccabeus] made atonement for the dead, that they might be delivered from their sin.” From the beginning the Church has honored the memory of the dead and offered prayers in suffrage for them, above all the Eucharistic sacrifice, so that, thus purified, they may attain the beatific vision of God. The Church also commends almsgiving, indulgences, and works of penance undertaken on behalf of the dead: