True, there is but ONE God. However, not everyone, not every faith or religion pray to the one God.
People search....their heart knows God exists, but, many are confused and get lost.
"Then one said to Him, 'Lord, are there few who are saved?' "And He said to them, 'Strive to enter through the narrow gate, for many, I say to you, will seek to enter and will not be able. When once the Master of the house has risen up and shut the door, and you begin to stand outside and knock at the door, saying, ‘Lord, Lord, open for us,’ and He will answer and say to you, ‘I do not know you, where you are from,’ then you will begin to say, ‘We ate and drank in Your presence, and You taught in our streets.’ "But He will say, ‘I tell you I do not know you, where you are from. Depart from Me, all you workers of iniquity.’ There will be weeping and gnashing of teeth...." Luke 13:23-28