A person who was a devil while alive, will still be one when lying in the casket. Eccl 11.3. It is disgusting to hear someone trying to preach a person into heaven at a funeral. No matter what might be said about a dead person, such words won?t help because the person will be judged by their works which follow them to the grave. Rev 14.13. Rev 20.12. Eccl 12.14.
If the deceased died not being pleasing to the Lord, that person will not enter heaven. John 8.21. Only people who have obeyed the Lords word will enter heaven, so it is very important that a person understands what the will of the Lord is. Matt 7.21. Eph 5.17
If something is to be said at a funeral about the deceased, it should be about the good things done or pleasant times one had with the deceased. But talking about the deceased being in heaven, etc. needs to be shunned. The deceased could have been engaging in secret sins which others knew nothing about. Psa 19.12-13. Psa 90.8
So go to the funeral and help comfort others as best as you can and leave the entrance into heaven to God. Luke 12.5.