"'For I know how many are your offenses and how great your sins. There are those who oppress the innocent and take bribes and deprive the poor of justice in the courts.'" NIV translation
God tells Israel that He sees what they do to the poor and that is something that we need reminded of as well. There are those who think that their lives are secret and they can do anything they want because they have money. Although that may seem to be true, everyone will answer to God on the last day.
"'Therefore the prudent keep quiet in such times, for the times are evil.'" NIV translation
"The prudent" speaks of those who are looking to the future. Those that are oppressing the poor are living for today and do not have a care about the ultimate tomorrow.
Those that are looking toward the justice that will come with Jesus Christ do not fight the system. The system is not going to get any better and is going to be removed at the return of Jesus. The prudent await the return of the ultimate Judge and focus on Him. There are many that want to reform this earthly system but, as we see in this verse, "the times are evil".
"'Seek good, not evil, that you may live. Then the Lord God Almighty will be with you, just as you say he is.'" NIV translation
God urges Israel to seek Him for He is the only thing that is totally good. Israel was claiming to be God's chosen people but were not seeking Him.
It is much the same today as many will attend a worship service once a week and then seek the things of this world the other six days. They will lie and cheat in business and are out for all they can get for themselves. They may even give a portion of what they get to a collection plate in hopes of making it right with God. That is the exact same thing that Israel is being warned about by Amos. We are free in Christ to enjoy the things of this world but God knows where our hearts are focused. Are we, like Israel, just going to claim to be Christians or are we going to walk the talk as Jesus did? For more on this topic, check out our Measure of a Man meditation.
"'Hate evil, love good, maintain justice in the courts. Perhaps the Lord God Almighty will have mercy on the remnant of Joseph.'" NIV translation
This verse speaks of a change of heart which is required for us to care about the poor or anyone else. That change of heart can only come from God with Him dwelling in us through the Holy Spirit. Once our hearts are changed, our actions will follow and glorify God.