Why I Reject Salvation by Works for any Dispensation

Because it did not happen when man had his best chance the dispensation of innocence

God created a perfect man. As the representative of all man, he must have been the best man who ever lived until the coming of Jesus Christ. He had great wisdom and a perfect moral character. He had no sin nature and was perfectly innocent.
God placed man in a perfect environment. The entire earth was climate-controlled. There was no sin, no bars, no hospitals, no wars, no famine and no reason to have any of these. Adam was given a help meet for him and had daily fellowship with God.
God made obedience a very simple thing. All Adam had to do was avoid eating of the forbidden fruit. The sin and its consequences were clearly defined. There was no mistake about when that line was crossed. Adam had no reason to want to cross that line.
Yet, Adam sinned in the one forbidden thing and lost his place in the earthly paradise. He did it willingly and with full knowledge of what he was doing. Satans one temptation was enough to bring mankind to his knees and ruin him inside and out.
Conclusion: If works-salvation did not happen under these best of circumstances, there is certainly no chance for it to work under the less favorable circumstances.

Because it did not happen under the law, the most works-oriented of the dispensations.

By obedience to the commandments (Exodus 24:1-8; Leviticus 18:5; Deuteronomy 27:26)
By the making of sacrifices (Leviticus 1:1-4; 4:27-35)

The first provision, obedience to the commandments, could not save man because no man could keep all the commandments (Ecclesiastes 7:20; Romans 3:19-20; 12-14; 8:3; Galatians 2:16; 3:10-12, 21-22; Hebrews 7:18-19)
The second provision, the making of sacrifices, could not save man because the blood of animals could not put away sin

The law did not provide eternal salvation at all but rather offered temporal purification for the Jews (Hebrews 9:13-14)

Israel, as a nation, had a special relationship with God (Deuteronomy 4:7; 5:26; Psalm 147:19-20)
God would meet with Israel and their priests in a special way (Exodus 25:21-22; 29:42-44; 30:6, 36; Numbers 17:4 [thou (singular)you (plural)]; cp. Exodus 20:18-21; 33:7)
God was to dwell among them (Exodus 25:8; 29:45-46; Leviticus 26:11-12)
As such, there was a great danger of defiling Gods tabernacle among them (Leviticus 15:31; Numbers 19:11-13, 20)
This explains the special significance of the commands for Israel to be holy (Leviticus 11:44-45; 19:1-2)
The sacrificial system allowed them to cleanse themselves from their filthiness so that God could continue to dwell among them (Leviticus 1:1-4; 4:35; 16:30; Hebrews 9:13-14)
They needed the sacrifices so that God would accept them (Ezekiel 20:40-41; 43:27)

Because the imputation of God's righteousness without the law is witnessed by the law and the prophets. (Romans 3:21-22)

By the law (Deuteronomy 7:6-9; 9:4-6)
By the prophets (Psalm 35:24; 71:1-3; 119:40; Isaiah 45:24-25; 54:17; 61:10; Jeremiah 23:5-6; Daniel 9:16)

Because the utter sinfulness of man makes him absolutely incapable of having any part in earning his own salvation (Romans 3:21-23, 10-18; Psalm 14:1-3; Ecclesiastes 7:20; Isaiah 64:6)
Because no man will have any right to boast or claim merit in heaven (Romans 3:27-28; 4:1-2; Ephesians 2:8-9)

If merit allows a man to glory in earning his salvation and this kind of glorying is wrong, then why is it wrong for us but all right for those in other dispensations?
If merit was wrong for Abraham (Romans 4:2), the great Old Testament saint who was called the friend of God (James 2:23), then why is it all right for other Old Testament saints?

Because works-salvation makes God a debtor to man, something He can never be. (Romans 4:3-5; 11:35)
Because Paul applied faith-salvation to Old Testament saints.

Because works-salvation doctrine for other dispensations does not remove doctrinal difficulties

There are verses in Pauls Gentile epistles that are used by some to teach works salvation (Romans 2:1, 6-10; 6:16-17, 21-22; 8:1 [compare 1John 1:7]; 8:12-14; 13:2; 14:22-23; 1Corinthians 6:9-11; 11:29; 15:1-2 [compare Hebrews 3:6, 14]; 16:22 [compare Hebrews 9:28]; 2Corinthians 6:17-18; Galatians 5:4, 19-21; Colossians 1:21-23; 1Timothy 3:6; 5:11-12; 2Timothy 2:12; Titus 3:10-11)
There are verses in the Jewish Epistles that clearly teach grace salvation (Hebrews 1:3; 2:9-11; 4:2-3; 5:9; 6:18-20; 7:19, 25-27; 9:13-14, 24-26; 10:10-14; James 1:18; 2:1; 4:5-6; 1Peter 1:3-5, 9, 18-23; 2:24; 3:18; 2Peter 1:1, 5; 3:15 [teaches same salvation as taught by Paul]; 1John 1:7; 2:2; 3:1-2; 4:9-10; 5:1, 4, 10-13; Jude 3-4, 24)
The answer is evidently not found in separating the epistles of Paul from the Jewish epistles with a great gulf. Rather, the answer is found in rightly dividing the passages in both of these sections of the Bible.

Because supposedly works-salvation passages in non-Pauline scripture are seldom hard to understand as grace-salvation doctrine. The exceptions are just that exceptions. Any man-made doctrinal system will always have problem texts.

CONCLUDING REMARKS

All who go to heaven will go there based on a threefold foundation: the grace of God, the blood of Christ, and the faith of man.
No man will ever make it to heaven based entirely or in part on his own works.
However, there are still dispensational differences in the way man comes to God for salvation.

The blood of Christ is applied at different times. Old Testament saints had to wait in paradise until Christ came to die on the cross. We have His blood applied at the moment of salvation.
The faith of man has not always had the same content. Abraham believed God. The disciples in the gospels believed in Christ as the Messiah. We believe in the death, burial and resurrection of Christ.
The grace of God is more apparent in this dispensation than it is in any other. That is why we call it the age of grace. But grace is found in every dispensation.