I have copied out the verses that you mentioned mainly for my own benefit. I have also underlined some portions that I assume you consider support your “clear and explicit teachings” contrary to my view.
John 6:37-40 (KJV): 37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out. 38 For I came down from heaven, not to do mine own will, but the will of him that sent me. 39 And this is the Father’s will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day. 40 And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.
John 6:64-65 (KJV): 64 But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him. 65 And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father.
John 6:70 (KJV): Jesus answered them, Have not I chosen you twelve, and one of you is a devil?
John 3:16 (KJV): For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
John 3:36 (KJV): He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.
John 5:24 (KJV): Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
John 10:27-30 (KJV): 27 My sheep hear my voice, and I know them, and they follow me: 28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand. 29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father’s hand. 30 I and my Father are one.
Most of the verses that you quote speak in absolute terms, but these need to be balanced with other Scriptures. If the true believers already have everlasting life, how can Paul still speak of “hope of eternal life”?
There is quite a difference betweeen "balanced with other Scriptures" and "pitting against other scriptures" and it is the latter you are inferring. The reason you cannot balance these clear unambiguous precepts with your view is because your view fails to properly discern that the human nature is multi-faceted and that God's provision of salvation is applicable to all facets. For example there is a past tense "eternal life" now in possession, of which all the above verses refer to. There is a present tense and future tense (which you allude to) but seem to want to pit against the past tense. The problem you are having is that your view of man cannot harmonize with God's provision for man's wholistic salvation.
For example, the past tense salvation and eternal life has to do only with the "spirit" of man and past tense completed salvation of that aspect of human nature. The past tense doctrine is called the new birth and the object of new birth is NOT THE BODY of man but the spirit of man - Jn. 3:6 - which due to quickening has present tense eternal life in the spirit which will never cease even when the physical body ceases (Jn. 11:26).
The future tense eternal life has to do with the future tense redemption of the physical body from the sin principle of corruption which only occurs at the resurrection - 1 Cor. 15:53-56.
However, you are attempting to PIT the past tense with the future tense as though they are not "balanced" with one another, when in fact, they are perfectly balanced, but totally pitted against your view of human nature.
The present tense "eternal life" has to do with the soul of man or the conscious self and how the conscious self redeems his time (Eph. 5:16) or loses his time. Time is redeemed or lost as one walks in the Spirit or after the flesh. This redemption has nothing to do with getting into heaven but in redeeming the present time for the glory of God and what one gets in heaven due to redemption of time (1 Cor. 3:12-15). This aspect of salvation of time, can be saved or lost, without loss of the soul.