Like every other word (in any language), the usage of ‘monogenes’ is determined by it context. It is true that it can mean only son (unique) but we must remember that the emphasis is on the word ‘Son’. Even if it is used to mean unique it must be saying that Christ is God’s unique Son – and we are talking here of pre-existence not the virgin birth at Bethlehem.
I think I am right in saying that in the Septuagint (Hebrew to Greek) the word ‘monogenes’ is used at least 5 times. Each time it pertains to an only child.
If it is said that the word ‘monogenes’ only means unique, then the question must be asked as to WHY Christ is unique? If the trinity doctrine is correct then all three are exactly the same so how can one divine being (Christ), if He is the same as the other two, be unique? As far as I am concerned He is unique because He is the only One begotten of God. The Holy Spirit is not begotten. The Scriptures and SOP use the word ‘proceed’.
As far as the EGW statement (underived life) is concerned, take a look at the top of page 60 here
As you can see, Ellen White was DESCRIBING the TYPE of life that was in Christ (divinity). Divinity is life underived etc. She was not saying Christ was not begotten.
For an understanding of her 1895 ‘begotten’ statement, go to the following link at the top of page 3 here
As you can see, Ellen White uses the word ‘begotten’ as a verb (a doing word), not an adjective. That really is very important. In other words, she was not saying begotten meant a unique son (which would have been an adjective) but that He was begotten as in a happening (an event) that took place. Read what I have said and you will see what I mean.
You may also like to read page 12 here
There can be no doubt that our early church, even through to the 1940’s and 50’s were still teaching that Christ is begotten of the Father. In fact in 1893 EGW said that our church was teaching the truth concerning Christ’s pre-existence. This was when they were teaching that Christ is begotten (an event that happened). Never did she say they were wrong in what they were teaching. It would be very odd if God allowed our church to teach error on the most important teaching of Scripture and not tell His prophet (not even in 71 years) that it was wrong. That really would be weird. Tens of thousands had come to believe what we were teaching.
The fact that this belief was endorsed through the SOP is one of the reasons why we held it for so long.
EGW’s statement in DA re underived life was not contradicting what Smith wrote. The two statements are complimentary. Christ was begotten of God therefore the TYPE of life that was in Him is life underived (divinity)
Throughout his book ‘Christ and His Righteousness’, Waggoner emphasised over and over again that Christ was begotten. He also did the same in his articles etc. There was never any problem within SDA’ism over this – at least not until there was a push from our leadership to change what we have been teaching throughout the 71 years of EGW’s ministry.
BTW, ALL the parties concerned at Nicaea said that Christ was begotten. This was the teaching that came down through apostolic times and through the early centuries of the Christian era. In fact Alexander (the Bishop of Alexandria), who today we would call a trinitarian (he opposed Arius), said that anyone who does not believe Christ to be begotten was mentally deficient.
I hope some of the above helps.
BTW, there is a huge study on ‘monogenes’ here