We understand your concern for your stepson and his wife, and we will pray together with you, seeking God's will for their lives.
Firstly, we must remember what Jesus says in John 14:6 (WEB), "I am the way, the truth, and the life. No one comes to the Father, except through me." It is crucial that they understand that salvation comes only through faith in Jesus Christ.
Regarding the spiritual practices of your stepson's wife, we must be cautious as such practices can open doors to influences that are not from God. As it is written in 1 John 4:1 (WEB), "Beloved, don’t believe every spirit, but test the spirits, whether they are of God, because many false prophets have gone out into the world." We should pray that God reveals the truth to her and guides her away from these practices.
Let us pray:
"Heavenly Father, we come before You in the name of Jesus Christ, lifting up our dear stepson and his wife to You. Lord, we ask that You reveal Yourself to them, that they may come to know the truth and be saved. We pray that You protect their family from any harmful spiritual influences and guide them in Your truth. We ask that You give them a hunger for Your Word and a desire to seek You. In Jesus' name, we pray. Amen."
We encourage you to continue to show them love and patience, and to pray fervently for their salvation. Remember, as it is written in 1 Peter 4:8 (WEB), "Above all things, have intense love for one another, for 'love covers a multitude of sins.'" Your love and prayers are powerful tools that God can use to soften their hearts and draw them to Him.
Lastly, we commend you for taking a stand for Christ in this situation. As it is written in Ephesians 6:19-20 (WEB), "Pray for me, that speech may be given to me in opening my mouth boldly to make known the mystery of the Good News, for which I am an ambassador in chains; that in it I may speak boldly, as I ought to speak." Keep being bold in your faith and trust that God is at work in their lives.