God hears private prayer
Jesus taught his followers to pray in private rather than seeking attention from others. He pointed to the Father who sees what is hidden, so a quiet prayer in a bedroom, car, hospital ward, or lonely kitchen is fully known to God (Matthew 6:6).
Being alone does not make your prayer weak. Hannah was so burdened that she prayed silently at the tabernacle in Shiloh, and Eli eventually recognised that she had been pouring out her soul before the Lord (1 Samuel 1:13-16). God saw what others could not see. You do not need a crowd, polished words, or a special atmosphere for him to listen.
But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
Praying together is a real gift
Still, Christians are not meant to bear every burden by themselves. After Peter and John faced threats in Jerusalem, they returned to fellow believers, who brought the situation to God together (Acts 4:23-24). Their shared prayer was followed by renewed boldness, and everyone gathered was strengthened by the Holy Spirit (Acts 4:31).
Corporate prayer gives people a way to stand beside one another. James calls believers to pray for one another in a setting of honesty, care, and healing (James 5:16). Sometimes you can pray clearly for a friend who feels numb or exhausted. At other times, their simple prayer may carry you.
And when they had prayed, the place was shaken where they were assembled together; and they were all filled with the Holy Ghost, and they spake the word of God with boldness.
Does a group make prayer stronger?
Not in the sense that several people can make God do what one person cannot. God's power is not limited by numbers, and he hears the faithful cry of an individual. James uses Elijah as an example of earnest prayer, even though Elijah prayed alone when rain returned after a long drought (James 5:17-18).
Jesus did speak of believers agreeing as they ask God, and he promised his presence where two or three gather in his name (Matthew 18:19-20). The nearby verses concern the careful work of addressing sin and seeking restoration within the church (Matthew 18:15-17). So this is not a formula for getting any result a group wants. It is a precious assurance that Christ is present with his people as they seek him faithfully.
For where two or three are gathered together in my name, there am I in the midst of them.
Make room for both
Jesus himself made time to withdraw and pray alone (Luke 5:16). At the same time, after his ascension, his followers gathered with one purpose in prayer as they waited in Jerusalem (Acts 1:14). Private and corporate prayer are not rivals. Each meets a real need.
Pray honestly when you are alone. Then, when you can, pray with a church, small group, family member, or trusted friend. You may need others to remind you of God's goodness today. On another day, your quiet, faithful prayer may be the encouragement someone else needs.