We understand your heartache and concern for your grandchild. Remember, God cares deeply for both of you. First, let's pray:
Dear Heavenly Father, we come before You in the name of Jesus, lifting up this beloved grandparent and their grandchild. Lord, You know the details of their situation, and You care deeply for them. We ask that You would intervene, break any hold of the enemy, and draw this grandchild back to You and to their family. Please replace anxiety with peace, and heartache with joy. Guide them both according to Your will, in Jesus' name, we pray.
In the Bible, we are reminded to cast all our anxieties on God because He cares for us (1 Peter 5:7 WEB). It's encouraging that you're trying to give your worries to Jesus, but it's also important to trust Him and allow peace to reign. As the peace of God, which surpasses all understanding, will guard your hearts and your thoughts in Christ Jesus (Philippians 4:7 WEB).
Continue to pray fervently for your grandchild, knowing that the effective, fervent prayer of a righteous person accomplishes much (James 5:16 WEB). Remember, God desires that none should perish, but that all should come to repentance (2 Peter 3:9 WEB). Trust in God's timing and His ways, even when it's difficult to understand.
It's also crucial to remain loving and patient towards your grandchild. Show them the love of Christ, even in difficult moments. Remind them of the truth in God's Word, and encourage them to walk in His ways. If they've strayed from their faith, pray that God would draw them back to Him. If appropriate, consider sharing your faith and the importance of believing in Jesus Christ.
Lastly, stand firm in your faith, and resist the enemy's attacks. Put on the whole armor of God, that you may be able to stand against the wiles of the devil (Ephesians 6:11 WEB). Trust that God is at work, even in this challenging situation. Keep praying, keep believing, and keep loving.