Gods gift of grace is free. The Holy Spirit is in me and can never be removed. We are new creations in Christ.
you say osas is dangerous well not believing it is dangerous, i take it you believe in 'states of grace' then? "be careful you die in a state of grace or you might not go to heaven." this is dangerous a false Catholic doctrine leading to doctrines of works.
The bible shows how these actions we need to do like repent are in fact due to the Holy spirit. john 3:5 titus 3:5 (rebirth), acts 11:15-18 1cor 2 9-12 (conversion),
romans 8:9 'You, however, are controlled not by the sinful nature but by the Spirit' v16 'The Spirit himself testifies with our spirit that we are God's children'. testifies is present, implying continuation. this testifying is not just a one off occurance but continues throughout a believers life.
eph 1:13-14 '...having believed, you were marked in him with a seal, the promised Holy Spirit, who is a deposit guarunteeing our inheritance until the redemption of those who are God's possesion - to the praise of his glory.' (preservation)