What is the relationship between the Gospel and good works/social justice ministries/mercy ministries? This is one of the current intramural debates among Christians. Paul actually addresses this issue in his epistle to Titus. The phrase good deed(s) is used six times in this short letter, and after dealing with the issue of establishing order-appointing elders-refuting and silencing false teachers (yes, they all go together), he emphasizes the role of good deeds in the life of the believer and therefore the life of the church.
In 1:16 we see that there are those who profess Christ but whose deeds deny him, and Paul calls them detestable, and worthless for any good deed.
In 2:7-8 Paul exhorts Titus, as the spiritual leader, to be an example of good deeds, which along with purity of doctrine, dignity, and soundness of speech, will put the opponents of the gospel to shame and give them no reason to malign Christians.
In 2:14 we see that Christ redeemed us from every lawless deed so that His people would be zealous for good deeds.
In 3:1 we see that we are to be in a state of readiness/preparedness for every good deed.
In 3:8 we see that we, as Christians, are to exercise thought in engaging in good deeds, and that these deeds are good and profitable for men.
In 3:14 we see that we must be in the habit of/accustomed to engaging in good deeds that meet pressing needs, so that as Christians we will not be unfruitful.
It is obvious that engaging in good deeds is a key theme in this book, something that Paul, speaking on behalf of the Lord, views as important. And if you follow the flow of thought concerning good deeds (from 1:16-3:14) you will see that deeds will either be contrary to and therefore contradict our doctrine and profession, or they (good deeds) will concur with and therefore confirm our doctrine and confession.
In reading this epistle we see that those who are not Christians are worthless for any (truly) good deed. We see that for Christians good deeds adorn the doctrine we preach, put the opponents of the gospel to shame and causes their maligning to fall flat. We see that, as Christians, we are to have a passion for goods deeds, to be always ready and prepared for good deeds, and are to thoughtfully engage in good deeds. These good deeds are beneficial to men, not just Christians but to men in general; and in performing these good deeds pressing needs will be met, and we will not be unfruitful (in other words, God will take them and use them for His glory...compare with John 15:1-11). As Martin Luther said, "Justification is by faith alone, but not by a faith that is alone."
Paul doesn't define what these good deeds are...probably because He knows that Christians who have a heart for good deeds and give careful thought as to when, where, why, and how, will not only be guided by the Holy Spirit in their endeavors; but through the Spirit will also be given the opportunities for them as well, as the Lord always matches God-given desires with God-given opportunities (see Psalm 37:3-6).
I don't think there is a tension between good deeds and Gospel proclamation...they do go together. How can you love someone enough to give them the gospel to meet their spiritual need, and not be moved to provide for their physical needs, or vice-versa? Doing one without doing the other tears the heart right out of the Gospel.
As is always the case, the Scriptures give us the mind of God concerning these issues. So instead of debating one another, let's get busy and stay busy doing all that the Scriptures tell us to do.