As believers we can't quite condemn as God can, but we can pray in hopes that maybe someday they will see. Perhaps, if the Spirit is in them, it should do the convicting and leading into the mystery of the Gospel. However, pertaining to the basis of Scripture, wherein stated to test the spirits whether they be of God or not, If they do not confess that Jesus Christ is Lord, then maybe it is more plain to conclude. We were also not of God at one point in our lives, so them too can be saved, and turned around, directed on the strait and narrow path of the one truth.
There is importance in stressing the divinity of Christ, because He himself proclaims He is the Truth, the Life, and the Way, no man comes to the Father but by Him. So they must see the necessity for mediation. If this Triune God lives in us, The Father, Son, and Holy Ghost, it is plain and simple what Scriptures like the majority of the book of the Gospel according to John, the first chapter of Hebrews and quite evidently, throughout the bible, it is thoroughly a well implied concept this including the Scriptural proofs of the Trinity, as well as the divinity of the Son.
As well known by many we are all at different stages of our walks wrought in Christ. So, perhaps words spoken will settle in, in time to come. To tell a brand new Christian who hasn't read much of anything in the bible, uh yes, Jesus Christ is God, he may wonder to himself, especially when the Trinity is mentioned. It is completely necessary to study to show yourselves approved before God, also to be well learned in Scripture, that you will not be tossed about on every wind of doctrine. So, that being said O' my fellow believers in Christ, seek wisdom and obtain understanding, never give in/up/out, the Truth will set you free.