From 1 John 4:7-11 we see the attitude of love we must have and the actions of love we must take are rooted in and flow from God’s love. But make no mistake: the love John writes about is no mushy sentimentality or mere friendly affection.
In 1 Corinthians 2:1-2, Paul tells them he proclaimed the testimony of God, the heart of which is Jesus Christ and His crucifixion. It was so important, he had determined to know only that among them.
When we have the attitude about ourselves and our relationship to Christ that the Christians in the first century had we will be properly equipped to be effective evangelists.