Sometimes, funerals are referred to as a celebration of life. This is a very fitting and appropriate way to remember the happy times and good aspects of the person who has departed. While funerals are often sad occasions, they can also be marked by joy when this is done. Especially if the the person was a follower of Christ and is now at peace with him.
Interestingly enough, Christians actually celebrate the death of Jesus. While it might seem odd to an unbeliever that we would celebrate the brutal crucifixion of our Lord; the fact is that apart from his death we would have no reason for hope. The death of Christ was not merely a case of jealous Jewish leaders conspiring against him, or of heavy-handed Roman leaders carrying out the deed. The death of Christ was a pre-ordained event, with eternal theological implications. In Acts 2, Peter preached to the Jewish people of his day saying, "This Man, delivered over by the predetermined plan and foreknowledge of God, you nailed to a cross by the hands of godless men and put Him to death. But God raised Him up again, putting an end to the agony of death, since it was impossible for Him to be held in its power.” (Acts 2:23-24)
Those who killed Jesus were responsible for their actions. Yet at the same time, his death was ordained for a divine and redemptive purpose. Christ's death was a sacrifice to pay the eternal price for all of those who trust in him. His death atoned for the sins of his people. It was ordained by the Father. And it was accepted by the Father. Furthermore, it was also the will of Jesus that he die, as he stated, “No one takes my life, but I lay it down of my own accord.” (John 10:18)
Jesus's death was unique in many ways. It was his death alone that paid the price for sinners like you and me. And it is through him alone that we can have forgiveness and eternal life. And in this fact, we rejoice. We rejoice that Christ died so that we might live. We don't glory in our sin that made it necessary, nor do we glory in the sinners who nailed him to the cross. But we do glory in a grace so profound that it would willingly die to pay the price for those who would kill him.