We are truly sorry to hear about your elder brother's disappearance, and our hearts go out to you and your family during this difficult time. We stand with you in prayer and seek God's will together in Jesus' name.
Firstly, we want to remind you that God is sovereign and all-knowing. He knows exactly where your brother is and what has happened to him. As believers, we trust in God's goodness and mercy, even in the most trying of circumstances. In Psalm 147:5 (WEB) it is written, "Great is our Lord, and mighty in power. His understanding is infinite."
We encourage you to turn to God in prayer, seeking His comfort and guidance. In Philippians 4:4-7, the Apostle Paul encourages us, "Rejoice in the Lord always! Again I will say, Rejoice... Let your gentleness be known to all men. The Lord is at hand. In nothing be anxious, but in everything, by prayer and petition with thanksgiving, let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your thoughts in Christ Jesus."
However, we need to address the fact your missing brother is an extremely serious issue. Your brother if alive, may be living a wayward and possibly immoral life. This may suggest that there are more important things then whether the Lord can supernaturally prophesy regarding his situation. It is far more important that he is saved from his sin and is reconciled to God and the family. In the Parable of the Prodigal Son in the Luke 15, a man had two sons. The younger left home, traveled far away, and lived a sinful life. When the son returned and repented, the father graciously received him back into the family. This parable shows a loving and faithful father welcoming back his repentant and wayward son. The Lord was certainly not saying this was allowable, rather then when there is repentance. This also the same Lord that was willing to provide that same wayward son his inheritance early, in part allowing such sin to happen. In many situations that we do not understand, this is a very important understanding.
Questioning whether we can prophecy in the name of the Lord is a serious matter. The prophet Jeremiah warned against false prophets who prophesy without God's authority in Jeremiah 23:21 WEB "I have not sent these prophets, yet they ran: I have not spoken to them, yet they prophesied." Furthermore, the Lord through Moses warned us in Deuteronomy 18:20-22, "But the prophet, who shall speak a word presumptuously in my name, which I have not commanded him to speak, or who shall speak in the name of other gods, that same prophet shall die. You may say in your heart, How shall we know the word which Yahweh has not spoken? When a prophet speaks in the name of Yahweh, if the thing doesn't follow, nor happen, that is the thing which Yahweh has not spoken: the prophet has spoken it presumptuously, you shall not be afraid of him." Here the Lord is warning us against attempting to prophesy in his name falsely. The consequences are serious enough to result in death and separation from the presence of the Lord. In this passage it is written in verse 21, 'You may say in your heart', we believe this may suggest that it is the Lord's will that we should use some discernment in such an issue. We feel it makes sense that this discernment is in the face of a prophet or someone making a prophecy. To ask us to prophesy is asking us to risk separation from God for eternity. There is nothing mentioned in this prayer request that allows us this discernment.
Here lies the most important thing about this prayer request. God has given us his Word, the Bible. We also have a path for a restored relationship with the living God, through his son Jesus Christ. We can reach God only through the restored relationship that God provided us through his son Jesus Christ. It is written in John 3:16-18, "For God so loved the world, that he gave his one and only Son, that whoever believes in him should not perish, but have eternal life. For God didn't send his Son into the world to judge the world, but that the world should be saved through him. He who believes in him is not judged. He who doesn't believe has been judged already, because he has not believed in the name of the one and only Son of God." The living God provided his son who was willingly crucified so that we can be saved from sin and a lost eternity. Notice in Matthew 9:6,"But that you may know that the Son of Man has authority on earth to forgive sins..." Then he said to the paralytic, "Get up, take up your mat, and go to your house.," In this passage our Lord Jesus Christ is showing us that all authority has been given to him in heaven and on earth, regardless of the laws of the religious authority of the time. So we believe we can say with confidence that prophesying as requested, for an unbeliever who has rejected Christ would not honor God or the sacred meaning of Christ's death on the cross and resurrection.
Now is a great time to bring it to the Lord in prayer.
Heavenly Father, we come before you today in prayer, asking for your guidance and wisdom.
Lord, we pray for things that the Lord desires to hear in this prayer. We pray that you would have mercy on this brother and that he is safe and healthy. We pray for his physical and material well being. We pray and know that all authority in heaven and on earth belongs to our Lord Jesus Christ. We pray for his heart to be softened and turned to the truth. If he does not know Christ, we pray that the Holy Spirit will convict him of his sin, the righteousness of Christ, and of his pending judgement if he chooses not to believe. That is is true and our desire that the Lord's will be done in this matter. We pray that he will believe and be saved and return to the family.
Father God, please give this brother's family Your strength as they wait for Your answers to their prayers. Please fill them with Your peace. In Jesus Christ name, we do pray for all to come to the saving knowledge of our Lord Jesus Christ. In Jesus Christ name we do pray.
We encourage you and your family to continue praying and trusting in God, knowing that He hears your prayers and is faithful to act according to His perfect will. Keep your hope anchored in Him, and may His peace comfort you during this time.