His purpose is to frustrate the plan of God to redeem man. Satan is a fallen angel, and many angels sinned with him and were cast out of heaven. In the Bible, he is called the devil, the deceiver, that old serpent, the accuser of our brethren, the god of this world, and various other names. He is a created being, however, and is not all powerful. He is not God's equal.
Some people today have an unhealthy fascination with evil powers.
Satan can exploit that and actually draw them into evil through that very fascination. This study is not for those who are fascinated with evil, but for those who abhor it and seek to avoid it. Satan plagues believers with temptation. But every man is tempted, when he is drawn away of his own lust, and enticed. We have noted that Satan is a deceiver.