The first letter of Peter (First Peter) was written to the Jews. The second was written to the believers and the Gentiles (Non-Jews). In the first eight verses of second Peter we are told all that is required of us. Investigate it in great detail, for it is somewhat different from what "mainstream" preachers would have us believe:

(NIV:)
1 Simon Peter, a servant and apostle of Jesus Christ, to those who through the righteousness of our God and savior Jesus Christ have received a faith as precious as ours:
2 Grace and peace be yours in abundance throught the knowledge of God and of Jesus our Lord.
3 His divine power has given us everything we need for life and godliness through our knowledge of him who called us by his own glory and goodness.
4 Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature and escape the corruption in the world caused by evil desires.
5 For this very reason, make every effort to add to your faith goodness; and to goodness, knowledge;
6 and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness;
7 and to godliness, brotherly kindness; and to brotherly kindness, love.
8 For if you posess these qualities in increasing measure, they will keep you from being ineffective and unproductive in your knowledge of our Lord Jesus Christ.

(Living Bible:)
From: Simon Peter, a servant and missionary of Jesus Christ.
To: All of you who have our kind of faith.
The faith I speak of is the kind that Jesus Christ our God and Savior gives to us. How precious it is, and how just and good he is to give this same faith to each of us.
Do you want more and more of God's kindness and peace? Then learn to know him better and better. For as you know him better, he will give you, through his great power, everything you need for living a truly good life: he even shares his own glory and his own goodness with us! And by that same mighty power he has given us all the other rich and wonderful blessings he promised; for instance, the promise to save us from the lust and rottenness all around us, and to give to us his own character.
But to obtain these gifts, you need more than faith; you must also work hard to be good, and even that is not enough. For then you must learn to know God better and discover what he wants you to do. Next, learn to put aside your own desires so that you will become patient and godly, gladly letting God have his way with you. This will make possible the next step, which is for you to enjoy other people and to like them, and finally you will grow to love them deeply. The more you go on in this way, the more you will grow strong spiritually and become fruitful and useful to our Lord Jesus Christ.

What, exactly, is meant by "good?"
Good is unselfishness. Putting the welfare of others before our own.
Naturally, the antithesis of this is selfishness.
Selfishness is not caring about others. That is Evil.
Satan's slogan is "Look out for number one."
Jesus' commandment to us is "Love one another." And by "one another," he most decidedly does not mean just fellow Christians, because he also said "Love your enemy." "If anyone asks you for anything, give it to them. If anyone steals anything from you, do not ask for it back. If anyone harms you, turn the other cheek. (Don't try to harm them back.) Do not try to get the speck out of your brother's eye. (Don't try to correct others, or make others behave.)" See, if you truly love someone, you not only love them in spite of their faults, you love them because of their faults, too. You love them for who they are, faults and all. We all have faults.

Christianity is not what most believe. It is not going to church every sunday, it is not abstaining from liquor, it is not refraining from cursing.

Christianity is loving one another. Jesus said so. "By this you shall know my disciples, that they love one another."(everyone)