Mark 16 mentions no water.
If A & B, then C;
If not A, then not C;
Illogical fallacy to conclude: If not B, then not C
(Logic 101).
FOR (EIS) has many meanings; not necessarily purpose.
English example, "He shouted for joy." (Man did not shout to obtain joy).
Acts 2 never mentions water with baptism; context is Spirit Baptism.
And it shall be, that whosoever shall call on the name of the Lord shall be saved. Acts 2:21
Whosoever rules out any essential addition. This is a call of faith.
Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.
Spirit baptism is what adds persons to the Body of Christ, not water immersion.
It is straw man to post verses in this context which direct believers to get baptized, as no one I have read has objected to water baptism. However, if you give it translated immersion, you may get opposition as there may be some sprinklers around.
Water immersion cannot save. The Bible never says that is saves. It is a human work, & human works cannot save.
Over & over the Bible offers salvation for ONLY BELIEVE, nothing else. Such language as whosoever /everyone who / all who believe(s), rules out any essential addition.
whosoever shall call on the name of the Lord shall be saved. -- how shall they call on Him in Whom they have not believed (Rom 10:13-14)
Act 13:48
And as the Gentiles heard this, they were glad, and glorified the word of God: and as many as were ordained to eternal life believed.
[NO WORKS, NO WATER]
Acts 15:8
And God, who knoweth the heart, bare them witness, giving them the Holy Spirit, even as he did unto us; and he made no distinction between us and them, cleansing their hearts by
faith.
[NO WORKS, NO WATER]
Acts 16:31a
And they said,
Believe on the Lord Jesus, and thou shalt be saved, . . . .
[NO WORKS, NO WATER]
Acts 26:18b
that they may receive remission of sins and an inheritance among them that are sanctified by
faith in me.
[NO WORKS, NO WATER]