I've looked back and wondered about this widely sung "hymn" myself. I grew up in a protestant church with considerable participation. Then, at some point, it became increasingly aggravating when some religionist would make a statement that God wanted us to do this or that. JUST HOW DO YOU KNOW THAT?
So this is where I am now:
1) The Bible is insufficient for giving the final rules. Anything can be supported with several sentences picked from anywhere in it. Do you take an eye for an eye, or forgive seventy times seven?
2) From reading Bart Ehrman (head of the religious studies department at UNC Chapel Hill) and others, we don't know who really wrote the Gospels. The first, Mark, appeared some 30-40 years after time claimed for the crucifixion, and contain the only "biographical" information available. No one involved is these ever saw or heard Jesus. Paul, who lived during the time of Jesus, also never saw or heard Jesus but claimed all of his writing came from "revelation".
3) Both Christian and secular scholars who actually study the Bible from an historical and literary standpoint agree that God is ineffable...meaning unknowable.
4) The massive "Christian" support for Trump, rapist and incredible liar, has really harmed the value of all the Christian dogma for me.
So when someone says that God wants us to line up behind this cross and march as to war, or to hurt some group or another because God wants it, HOW DO YOU KNOW THAT?
BTW. I still have a very strong spiritual life.