Yet, it's a frequent belief in Christianty that Eternal Security is a doctrine of the devil. Why? Because the Apostles talked about it and they're of the devil? That's essentially what they're saying.
Not at all. Eternal Security does not stand up to the test of scripture. Hebrews is a book given to us to warn us not to slip away.
Heb 2:1 Therefore we ought to give the more earnest heed to the things that were heard, lest haply we drift away from them.
Heb 3:12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
Heb 6:4-6 For as touching those who were once enlightened and tasted of the heavenly gift, and were made partakers of the Holy Spirit, and tasted the good word of God, and the powers of the age to come, and then fell away, it is impossible to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
You can be "once enlightened" , by the "Holy Spirit", then "fall away".
Our security is based on the cross, yes, and by grace, but it is not guaranteed.
Heb 10:35-38 Cast not away therefore your confidence, which hath great recompence of reward. For ye have need of patience, that, after ye have done the will of God, ye might receive the promise. For yet a little while, and he that shall come will come, and will not tarry. Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him.
2Pe 1:2-10 Grace and peace be multiplied unto you through the knowledge of God, and of Jesus our Lord,
According as his divine power hath given unto us all things that pertain unto life and godliness, through the knowledge of him that hath called us to glory and virtue: Whereby are given unto us exceeding great and precious promises: that by these
ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust. And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; And to knowledge temperance; and to temperance patience; and to patience godliness; And to godliness brotherly kindness; and to brotherly kindness charity. For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ. But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
When we are saved the Holy Spirit empowers us to leave behind our sins, we share in the Divine nature. It is our job to maintain, and add to our virtues, with the assistance of God, who strengthens us as we seek Him daily.
2Ti 2:19 Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one that nameth the name of Christ depart from iniquity.
Mar 14:38 Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.