Sound Doctrine Is Not Optional
If you're going to enter the ministry, whether as a missionary or a pastor, you will spend the rest of your life (if you're faithful) teaching sound doctrine. That's what you will do.
So systematic theology—biblical doctrine—is not optional. You can't say, "Well, I'm not really interested in doctrine, I just want to minister to people." The only way you can minister to people is to teach them what God has revealed as true.
We live our beliefs. People have to believe in something. We live in a day of tolerance and wanting to let everyone have their own viewpoint—your truth and my truth might be two different things, but we're each entitled to our own truth.
That is an absolute lie. There is absolute truth—the truth contained in Scripture. You have to understand the truth of Scripture because that is what ministry is—it is conveying and communicating sound doctrine so that people can understand it, then believe it, then hold it as a set of convictions, and then live it and declare it.
God wants Christians to share his holiness and to present themselves as slaves of righteousness, which will result in holiness.
God’s decree is his eternal plan, whereby, according to his decretive will and for his glory, he foreordained everything that comes to pass.
John MacArthur discusses the historicity and significance of Adam in the Bible.