We are the children of God, see what love He has lavished upon us !!!
Since we are born of God, born of the will of God...who "UN-borns" us ?
Scripture tells us we can.
Who cancels, negates, and nullifies our spiritual birth ? Who has the power ?
Scripture tells we can.
Our new nature was born of God, not of ourselves, it cannot be returned.
But it can be corrupted, and lost; which is what Scripture tells us.
If as humans, we love our children in spite of whatever problems or faults they have, how much more will The Father of Spirits love us unconditionally ? If we subscribe to a returnable salvation or a salvation with an expiration date, then God did not really love us in the first place. God would knowingly be giving us the promise of eternal life, only to revoke it later ?
The problem with your assertion, is that you forget we are human beings. God gave us free will, correct? That is what makes us in His image. Thus He will not go against that will, because of His love for us. Sin keeps us out of heaven, correct? The teaching from the Book of Revelation is very explicit in that point. God is not going to force anyone to go to heaven. That is the reason why it requires a choice from us, for redemption to be applied to us. We must BELIEVE and be BAPTIZED (Mk 16:16). We must also DAILY pick up our crosses and follow Him. (Mt 10:38, 16: 24). We must abide in Him, by keeping His commandments. (Jn 15: 6-10)
There is not a promise that we can keep.
But, God keeps all his great and precious promises.
You are right, that isn't a promise we can keep, by ourselves. That is the reason, why we need the grace of God to grow in us, each and every day. That is the reason why we need a God who is willing to forgive us our trespasses, as we forgive those who trespass against us. So that when we do fall, we have a means to be reconciled back to Him.
Salvation is not a one time event. Salvation is a life, which we must lead from our initial conversion, our baptism, partaking of the Lord's table, keeping His commandments, and picking up our crosses and following Him wherever He leads us. It is as simple as that.
Don't get me wrong. I get why the OSAS idea is enticing; because it allows people to get their cake and eat it too. You can be saved and do all the sinning you want, with a clear conscience; because you are not sinning, but the devil inside you is the one sinning. But even though it is enticing, it doesn't make it right. Like I said before, you really have to throw a lot of Scripture away, to accept OSAS. And that I am not willing to do.