It is probably a frightening oversimplification to claim that when the early Church emphasized Jesus' humanity she spawned great social programs and when she emphasized his deity produced great theology. Understanding and expressing the reality of these two natures existing in a single person inspired the historic schisms. To this day we quibble about the deified power of Christ to save and the incarnational power of Christ to serve, as if they were at odds with one another.
This tension between social justice and evangelism - or Christ as Man and Christ as God - is a bit like the tension between LOVE as verb (I love) and LOVE as noun (my love) - it works great both ways, it just depends on what you are trying to say. In fact the noun and verb can have a symbiotic relationship, "A lover loves." I become the noun, a lover, when I consistently engage the act of loving.
I am grieved when Christians feel like an invitation to accept Jesus is the only way to legitimize the protesting of evil or need to throw an altar call in when feeding the homeless, as if confronting evil or doing good were not enough. Jesus held up a Samaritan as the picture of what it meant to inherit eternal life by fulfilling the law of loving your neighbor (Lk 10) even though he had substantial theological issues with what Samaritans believed (Jn 4). Hating evil and loving justice do not need an evangelistic call in order to become valid. Those actions please Jesus all by themselves.
I am grieved when I meet Christians who have no problem protesting unfair wages for migrant farmers but have no desire to call people into a saving relationship with Jesus. How can we see the kingdom come without inviting others to acknowledge the King? Justice flows from a Judge and answering Jesus' question, "who do you say I am?" matters. A friend of mine, Doug Schaupp, observes that it is easier for him to take someone who is good at evangelism and turn them into a lover of justice than to take a socially active Christian and grow them into a good evangelist. That is sad to me.
Separating social justice and evangelism is like getting married and then not living together. Is it better to have the security of a marriage covenant and never see your spouse, or to live together with no real commitment or promise? I want both. Some of us may be more gifted at the prophetic confrontation of evil systems and structures and others at calling people to say yes to Jesus' invitation to trust him for salvation, but we must remain stoutly committed to both.
Jesus as God and Jesus as man, separating those things is heresy.