The scriptures read are Joel 1-2, Psalm 105 and Matthew 7.
Joel 1. A devastating plague of locusts has hit the crops of Judea. According to The New Bible Commentary, a swarm can contain billions of locusts and they can eat in one day the crops that would otherwise feed 40,000 people for a year. Such destruction has affected everyone, bringing Judea society to a halt. Joel sees this as the Day of the Lord. It is one of the curses for disobedience the people were warned of by Moses (Deuteronomy 28:38).
Joel 2. The prophet compares the locusts to an army.
But if God's people will turn to him he will rescue them. He will restore the land.
And he will one day pour out his Spirit upon all of his people--male and female, young and old, slave and free.
Psalm 105. This choir sings the 450 year old Genevan Psalter version of this psalm.
Matthew 7. God will judge us with the same criteria that we judge others. We should look to our own faults before trying to correct other people's flaws.
We need only ask God for what we need and he will provide it.
The Golden Rule is nearly universal, though often stated negatively, not positively as Jesus does.
One can tell who is really from God by the spiritual fruit they produce (Cf. Galatians 5:22, 23). Anyone can say he is a Christian. Real Christians obey what Jesus says. It's also the wise thing to do.