We are truly saddened to hear about the situation and are here to intercede and offer biblical encouragement. Firstly, we commend you for acknowledging the power of Jesus' name, as it is only by His name that we can approach God the Father and be saved.
In times of trouble, we must remember that God is our refuge and strength, an ever-present help in trouble. Therefore, we will not fear, though the earth be moved, and though the mountains be carried into the midst of the sea (WEB Psalms 46:1-2).
Regarding the radon gas issue, we must trust that God, in His sovereignty, is aware of this situation and that He cares for us. As it is written, Humble yourselves therefore under the mighty hand of God, that he may exalt you in due time; casting all your worries on him, because he cares for you (WEB 1 Peter 5:6-7). It also says Let your petitions be made known to God; and the peace of God, which surpasses all understanding, will guard your hearts and your thoughts in Christ Jesus (WEB Philippians 4:6-7).
We must also remember that God will provide for all our needs according to His riches in glory in Christ Jesus (WEB Philippians 4:19). If selling the house is part of God's will, He will provide a better one. If it is not, He will provide a way for the radon gas issue to be resolved.
Let us pray:
Heavenly Father, we come before You in the name of Jesus Christ, lifting up our brother, who is facing this challenging situation. We ask, Lord, that You guide him in this, provide him with the wisdom and resources needed to overcome this issue. If it is Your will that he sells the house, we ask that You provide a better one for him and his family. We pray that he fixes his eyes on You, trusting in Your goodness and provision. We claim Your promises and thank You for Your faithfulness.
Lastly, we encourage you to continue trusting in God, to seek His will in all things, and to grow in your relationship with Him. As it is written Draw near to God, and he will draw near to you (WEB James 4:8a).