No, Otherwise, God is a liar, and did not keep his promise.
to me that is dualism, that is placing conditions on one person (pre-cross/tribulation) to be saved, and no conditions on others (people of the church age) who are saved by grace through faith alone..
God keeps his promise. David understood eternal life.. He understood faiht, He understood sacrifice and burnt offering God did not desire.. He understood he was saved.
The seal is not for our benefit, it is for Gods.. When Jesus died, he died for everyone, Old testament, New testament, tribulation, Kingdom age..
all men everywhere were saved by faith in Christ (abraham believed God and it was credited to him for righteousness) this same righteousness is given to us..