Luther did not want to bring schism on the Church

I do not like and I never shall like a schism. Since on their own authority the Bohemians have separated from our unity, they have done wrong, even if the Divine right had pronounced in favor of their doctrines; for the supreme Divine right is charity and oneness of mind.

…I repulse the charge of Bohemianism. I have never approved of their schism. Even though they had divine right on their side, they ought nor to have withdrawn from the Church, because the highest divine right is unity and charity.”

Martin Luther
Debate in Leipzig between Luther and Eck
July 4th, 1519

Christianity is about the death of death

Christianity is a belief, first of all and above all, in the fact that Christ did not remain in the grave, that life shone forth from death, and that in Christ’s Resurrection from the dead, the absolute, all-encompassing law of dying and death, which tolerated no exceptions, was somehow blown apart and overcome from within.

Fr. Alexander Schmemann
The Christian Concept of Death

Not everything is found in Holy Scripture

If, for these and other such rules, you insist upon having positive Scripture injunction, you will find none. Tradition will be held forth to you as the originator of them, custom as their strengthener, and faith as their observer. That reason will support tradition, and custom, and faith, you will either yourself perceive, or learn from some one who has.

…This instances, therefore, will make it sufficiently plain that you can vindicate the keeping of even unwritten tradition established by custom; the proper witness for tradition when demonstrated by long-continued observance.

Tertullian
The Chaplet
Chapter IV