Salvation can not be lost.
Only the lost will take the mark.
YOU are very mistaken, You can lose your Salvation, very Much SO, Jesus says HE that endures till the end, the SAME SHALL BE SAVED,
2 Peter 2:21 For it had been better for them not to have known the way of righteousness, than, after they have known [it], to turn from the holy commandment delivered unto them.
2:22 But it is happened unto them according to the true proverb, The dog [is] turned to his own vomit again; and the sow that was washed to her wallowing in the mire.
YOU NEED to see that they where washed, And the only way that you can get washed from SIN ,IS BY THE BLOOD OF THE LAMB,
1 John 5:16 If any man see his brother sin a sin [which is] not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.
This also tells us if we see A brother sin that he will be lost if he dose not repent of the sins that he is committing.
Matthew 24:48 But and if that evil servant shall say in his heart, My lord delayeth his coming;
24:49 And shall begin to smite [his] fellowservants, and to eat and drink with the drunken;
24:50 The lord of that servant shall come in a day when he looketh not for [him], and in an hour that he is not aware of,
24:51 And shall cut him asunder, and appoint [him] his portion with the hypocrites: there shall be weeping and gnashing of teeth.
THis also shows us that if we don't keep GOING we WILL LOSE OUR SALVATION.
GOD has cast Satan out of heaven for sinning, AND HE IS NOT GOING TO LET US IN HEAVEN IF WE continue in sin,
And this verse makes it very plain,
Hebrews 10:26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
10:27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
10:28 He that despised Moses' law died without mercy under two or three witnesses:
10:29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?