Adventist News Network, October 16, 2014 -- http://news.adventist.org/en/all-news/news/go/2014-10-16/suggested-revisions-to-adventist-church-manual-include-matters-on-discipline/

“The proposal on ‘unauthorized speakers’ sought to remove details about who other than credentialed ministers can have speak from the pulpit. ... The new wording states: ‘Only speakers worthy of confidence will be invited to the pulpit by the church in harmony with guidelines given by the conference. Individuals who have been removed from membership or designing persons who have no authority from the church, should not be given access to the pulpit.’
“Harald Wollan, secretary of the Church Manual Committee, explained that the change would allow churches to adhere to the manual.”

God says:

1 Thessalonians 5:19-21
Quench not the Spirit. Despise not prophesyings. Prove all things; hold fast that which is good.

The Great Controversy, p. 64
“The church in the wilderness,” and not the proud hierarchy enthroned in the world's great capital, was the true church of Christ, the guardian of the treasures of truth which God has committed to his people to be given to the world.

Conclusion:

• Why are non-SDAs, and even pastors from other denominations, invited to speak in SDA churches?
• Why are public officials welcomed to the pulpit and given awards during the Sabbath morning divine service?
• Who decides what constitutes a “designing person?”
• Why are conference officials the ones to decide who may preach?
• The church is composed of its members; they are the ones who ought to decide.
• The Church Manual is not a divinely-inspired document.
• Should not the church follow what the Scriptures say?