It has been asked if the prayer has to be specifically in the name of Jesus to be valid. I think that this misses the role that faith plays in prayer. If prayer is the conversation of the believer with God, then anything without faith in the true God (Father, Son, and Holy Spirit) fails to really be a prayer. It may contain familiar, biblical-sounding words, but they are still just words spoken apart from faith.
I think of Matthew 7:21 - “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven.
And what is this "will of God"?
For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day.” - John 6:40
Can those who fail to believe in the Son truly pray to God?