Isaac Wardell with BiFrostArts.com helpfully explains what we want of people singing together. We are not promoting "hymn sings" as Isaac mentions, but the heart of what Isaac is getting at where we sing together. And we want people to sing together regardless of style, genre, or song. Isaac ends the video by how songs bring different ages together, but we see the gospel as the unifier and cause of singing. The point of singing is the One who caused a song in us and caused us to come together as a "host (crowd) of voices" as Isaac mentions. The Bible's word "church" comes from the Greco-Roman time period referring to people who gather as part of their life for a certain reason and belief to learn and live by their convictions.
Therefore, the Christian church is people who believe in Jesus the Christ (the God-man) and the good news about his person and work to live, die, and resurrect on behalf of the world to reconcile people to God the Father.
We all sing for whatever reason such at concerts, sporting events, national celebrations, art, culture, and so on. Uniquely, as a local Christian church comes together unified in their humbled belief in Christ that causes them to sing. Sometimes it's silent contemplation or anthemic joy. This becomes a part of a Christian's worship, which is a life poured our or lived for God, his plans, by his desires, for his glory.
Imagine when friends join a gathering time and connect the dots from one's real life beyond the gathering and recognize the realness of then the "host of voices" convictionally, anthemically, and humbly singing about the truth that transforms. God works not merely to change songs and voices, but hearts and lives that end up singing songs together about and to him.
