True worshippers worship God, and beside Him there is no other God. These are the only two qualifiers. Once we recognize who we worship, we must attend to how we worship. Not everything being done in the name of worship today, qualifies. Singing is a legitimate way to worship, but not everyone singing is worshipping.
Some people sing to hear themselves sing.
They are more concerned about themselves than they are with the One to whom we sing. Praising God is a legitimate way to worship God, but not everyone making a lot of noise is worshipping God. Sometimes the noise is simply a means to manipulate the emotions of the people. Or, even worse, an attempt to manipulate God. In this case the praise is a vain attempt force God into attending a meeting where He is not the center of attention, we are.