Not all Christians are given the gift of ministering or witnessing. "But the manifestation of the Spirit is given to each one for the profit of all: for to one is given the word of wisdom through the Spirit, to another the word of knowledge through the same Spirit, to another faith by the same Spirit, to another gifts of healings by the same Spirit, to another the working of miracles, to another prophecy, to another discerning of spirits, to another different kinds of tongues, to another the interpretation of tongues." (I Corinthians 12: 7-10, NKJV) There are ministries that witness to homosexuals, to call for their repentance and salvation, but not all Christians are called to such ministries. Others are called for the ministry of discernment, such as those who recognize the immoral nature of homosexuality as well as an agenda on the part of homosexuals and their allies among secular humanists and Marxists to overthrow Christian influence and Biblical morality in America and the West. Neither are all Christians called to this type of ministry. Christian believers are part of the spiritual body of Christ. Paul's analogy of the church to a body indicates that both types of ministry, and others as well, have their proper role. As Paul stated in I Corinthians 12:11 (NKJV): "But one and the same Spirit works all these things, distributing to each one individually as He wills."
To take Christ's words regarding judgment in the Sermon on the Mount to mean that we are to suspend discernment and suppress wisdom is against the whole counsel of Scripture. "Or do you not know that the saints will judge the world? If the world is judged by you, are you not competent to constitute the smallest law courts? Do you not know that we will judge angels? How much more matters of this life?" (I Corinthians 6: 2-3, NASB) The power that Christ gave the church to "bind and loose", the admonition of Paul to church discipline in I Corinthians 5, the "sword" given to the civil magistrate in Romans 13, the praise Luke gives to the people of Berea in Acts 17 for examining the Scripture daily all imply the power of judgment is in the hands of the Christian believers, the church, and the civil authorities.
The true context of the admonition in the Sermon on the Mount is with respect to unjust judgment. As an analogy, the condemnation of adultery, homosexuality, bestiality, etc., does not mean that the Christian faith is opposed to sex. Rather, it is commended within the bonds of traditional matrimony, even if condemned elsewhere.