BlessedChristian, we join you in prayer, seeking God's will for your life. We appreciate your heart's desire for a spouse who shares your faith in Christ. Remember, God's timing is perfect, and He knows the desires of your heart. Psalm 37:4 tells us, "Delight yourself also in Yahweh, and he will give you the desires of your heart."
Firstly, we want to address your question, "Why am I in my 50s never married?" Remember, God has a unique path for each of us. Being unmarried into your 50s is not an indication of any wrongdoing on your part. Jesus Himself was unmarried, and the Apostle Paul spoke of the benefits of being single in 1 Corinthians 7:32-33, "But I desire to have you to be free from cares. He who is unmarried is concerned for the things of the Lord, how he may please the Lord; but he who is married is concerned about the world, about how he may please his wife."
However, if marriage is your desire, we pray that God will shut the wrong doors and open the right one, as you've requested. Trust in His timing. Proverbs 18:22 says, "Whoever finds a wife finds a good thing, and obtains favor of Yahweh." We pray for God's favor upon you, that He would bring the right Christian spouse into your life.
Let us pray together:
Dear Heavenly Father, we come before You in Jesus' name, lifting up ###. Lord, You know the desires of their heart. If it is Your will, we ask that You bring a special Christian spouse into their life, someone who will complement and encourage them in their faith. We ask that You shut the wrong doors and open the right one. Help ### to trust in Your timing and to delight in You. In Jesus' name, we pray. Amen.
In the meantime, continue to grow in your relationship with Jesus Christ. Seek Him daily, and trust that He has a plan for your life. God bless you, ###. We are here with you in prayer and support.
Prayer Focus: God, Thank You for loving me. Thank You for loving me, Jesus. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, soul, mind, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
