Several Answers There are several answers to this question and lengthy introduction. (1) Seminaries First note that quite a few Denominations sponsor or support several Bible Colleges and Seminaries. Scholarly researchers usually congregate in the seminaries. AND is is the custom and habit for one or more of them to write and publish Systematic Theologies.
In most of these Systematic Theologies there is an opening section dealing with the Existence and Attributes of God. Quite a few give an expose of several of the "proofs of God's Existence." (Anthropological, Cosmological, Teleological, Historical, etc.) These books would be as close as one could come to obtaining OFFICIAL BELIEFS of any denomination. And any "evangelism" would be based on these truths. Seminarians would take courses on this type of philosophical and logical Apologetics, and incorporate it into their church which they would pastor. Evangelism in the local church would have a scholarly foundation.
- Louis Berkhof
- Augustus Strong
- Henry Thiessen
- Charles Hodge
- John Mueller
- Robert Dabney
- Thomas Aquinas
- Donald Macleod (?)
(2) Para-Church Orgs Some denominations are not capable of establishing A Seminary, or do not have seminary professors efficient in Evangelistic Apologetics. The local churches in these denominations are therefore reliant upon Para-church organizations for training their congregations on evangelizing atheist, agnostics, and skeptics. These organizations have highly skilled researchers, lecturers, disciplers, whom local churches can resort to for wisdom in reaching the unbelievers. A few of these are:
- Campus Crusade for Christ (Cru)
- Socrates in the City (Eric Metxas)
- Discovery Institute
- C.S. Lewis Society
- Institute for Creation Research
Denomination boards would examine and consider recommending one or more of these that are compatible with their denomination creeds. This would be surrogate OFFICIAL ADVICE, for which the OP asks.
Many of these organizations have lecturers and seminar speakers available for ministering in local churches. As well as literature, videos, a discipleship programs. Beyond this there is a plethora of web sites dealing with a philosophical, scholarly approach to evangelism, that denominational pastors could use as a resource.
John Lennox, Norman Geisler, Jason Lisle, Gary Parker, Jonathan Wells, Lee Strobel, Eric Metaxas, Petr Kreeft, William Lane Craig...are all knowledgeable scholars, who are able to give Official Advice on dialoging with unbelievers.
Unreasonable Resignation The middle paragraph of this OP presented an unreasonable resignation, throwing up his hands in defeat! It ignores the facts of the conversion of even the hardest of skeptics in history. And it displays an ignorance of the many ways unbelievers come to faith. And it is unaware of the purpose of "reasons, proofs, logical arguments, etc." (Most dialog is "pre-evangelism. Logical reasons dropped in the mind become tools for the Holy Spirit to work with.)
Most of the confrontation/gentle dialog with atheists and agnostics is
(a) pulling weeds (dealing with misinformation and disinformation about God),
(b) planting seeds (seeds of doubt concerning the inadequacies of the atheistic worldview,
(c) fulfilling needs (even atheists need friends and are human with many mortal-type needs; love can bring a mighty man to his knees),
(d) performing deeds (prophecies, see 1 Corinthians 14:24-25, healings 1 Cor. 2:4-5, Heb. 2:4, charity),
(e) explaining Creeds (many college atheists haven't a clue what Christianity is all about! Spiritually challenged they are! Also note how many biblical questions contestants on Jeopardy are unable to answer.)
The Holy Spirit is able to use many different tools to change the Minds and Wills of even the hardest skeptic. Scientists have come to faith by intellectually trying to resolve the "design" in the universe. Pondering the existential meaning of the universe has opened the minds of some. The logical bankruptcy of the Atheistic worldview has led others to consider Theism.
Paul and Areopagus In Acts 17:17 we see that the Apostle Paul was not hesitant to use metaphysical arguments in addressing the scholars of Athens. (cosmological, teleological, anthropological) He was so successful that "among a number of others," Dionysius, one of the scholars, became a convert! Men and women were convinced.
Note that when Paul referred to the "wisdom of men" in 1 Corinthians 1:21, he was referring to the philosophies of the Stoics, Epicurians, Pythagageans, and Platonic Athenians. He was NOT being adverse to Apologetics. The way a word is defined and used is determined by its context. So here "wisdom" was referring to the philosophies invented by men only.
But "wisdom," in reading the whole counsel of God, is a blessing and creation of God. In fact, most do not realize that wisdom was the very first thing created!
The Lord brought me forth as the first of His works, before His deeds of old; I was appointed from eternity, from the beginning before the world began. (Proverbs 8:22,23)
By wisdom the LORD laid the earth's foundations; by understanding, He set the heavens in place; by His knowledge the deeps were divided, and the clouds let drop the dew.
So God is not adverse to "wisdom" and its use by His disciples to convince unbelievers of the existence of God and their need to convert. Anyone who comes to salvation must believe He exists first. (Hebrews 11:6) Then they can live a life of faith that He will reward all those seek Him earnestly.
Apologetic reasonings are not the Gospel, but they lead men to the Author of the Gospel. Holy Spirit anointed Apologetics is the grease on the door of the closed mind so it will open easily when Christ comes knocking.