To maintain a high moral standard Peter advised Christians to

This question is asking what Peter advised Christians to do in order to maintain a high moral standard. The options provided are: A) marry fellow Christians, B) abstain from social vices, C) treat people fairly, and D) be merciful and kind. The correct answer is D, which means that Peter advised Christians to be merciful and kind to maintain a high moral standard.

As Christians, it is important to maintain a high moral standard. Peter, one of the apostles of Jesus Christ, advised Christians to do certain things in order to achieve this. One of those things is to be merciful and kind. This means that Christians should show compassion and understanding to others, even in difficult situations.

Being merciful and kind involves treating others the way you would like to be treated. This is known as the Golden Rule, which is a key teaching in Christianity. It is important for Christians to show mercy and kindness to others, as it reflects the love of Christ and helps to maintain a positive Christian image.

While the other options listed in the question are also important for Christians to follow, such as treating people fairly and abstaining from social vices, being merciful and kind is a crucial aspect of maintaining a high moral standard as a Christian.