Paul had presented the truth in a reasonable and logical fashion. His words were convincing--so much so that his rationale for living as a Christian almost persuaded Agrippa to become one. It is unknown if the king ever obeyed the gospel. However, the point I want to emphasize is this: Paul had evidently shared many good reasons for living as a Christian; otherwise Agrippa would not have been even partially persuaded.
We too must understand and share with others the reasons for living as a Christian. There are many internal reasons for living life as a Christian--namely, peace, hope, joy, purpose, etc. But, there are also some good external reasons for living as a Christian. Let us consider three of them at this time.
ONE REASON FOR LIVING AS A CHRISTIAN IS TO SAVE OTHERS.
In I Peter 3:1,2, Peter speaks to wives who have husbands who are not Christians. They are told to "be submissive to your own husbands, that even if some do not obey the word, they, without a word, may be won by the conduct of their wives, when they observe your chaste conduct accompanied by fear." Notice that the wife is told what to do, and she is also told why she is to conduct herself that way. Basically, her life is to be lived in such a way that she may have a strong Christian influence and save her husband. Friends, that is one reason for living as a Christian--to try to save others who are lost (whether they be family members, friends, neighbors, or complete strangers).
A SECOND REASON FOR LIVING AS A CHRISTIAN IS TO SILENCE THE OPPOSITION.
This truth is certainly seen in the language of Paul to Titus - "Likewise, exhort the young men to be sober-minded, in all things showing yourself to be a pattern of good works; in doctrine showing integrity, reverence, incorruptibility, sound speech that cannot be condemned, that one who is an opponent may be ashamed, having nothing evil to say of you" (Titus 2:6-8). Christian men should behave in a manner in which nobody can have any real reason to speak against them. Living a sincere and genuine godly life will help silence the opposition. This was true in the case of Daniel (e.g., Dan. 6:4,5).
A THIRD REASON FOR LIVING AS A CHRISTIAN IS TO SUPPORT THE TRUTH.
Paul wrote in Philippians 1:27 - "Only let your conduct be worthy of the gospel of Christ..." This passage calls for living a life that is in harmony with the gospel--a life that supports the truth. A life like this will attract people to the gospel rather than repelling them (as hypocrisy typically does). For example, in the parable of the good Samaritan the priest and Levite passed by on the other side of the road and did not stop to help one in great need (Luke 10:30ff). How many people would be willing to listen to either or these men talk about the importance of being caring and helpful? Not very many, I am sure. Some would be willing, however, to listen to a compassionate man like the Samaritan. Simply put, if our conduct is incompatible with the message we are speaking (the gospel), then we will not persuade anyone to adopt the Christian life.
Indeed there are many reasons (both external and internal) for living life as a Christian. Truly, there is no better way to live than as a child of God! Let us strive to fully comprehend the beauty and excellence of Christian living and do all that we can to persuade others to adopt this blessed lifestyle!