Paul presented the same foundational truths regarding Jesus Christ and the resurrection everywhere he went.  And although it was a new doctrine to the Athenians, Paul did not spend his time trying to tell or hear some new thing as they did.  When the focus of our believing is "some new thing" rather than the foundational truths of God's Word we have no root in the Word and we get blown about by every new doctrine that comes along.  It is important that we become well grounded in the foundation of Jesus Christ.

I Corinthians 3:10-11
   According to the grace of God which is given to me [Paul], as a wise masterbuilder, I have laid the foundation, and another buildeth thereon.  But let every man take heed how he buildeth thereupon.
   For other foundation can no man lay than that is laid, which is Jesus Christ.

   The foundation in which we are to become grounded and settled is the Lord Jesus Christ.

Ephesians 2:18
   For through him [Jesus Christ] we both [Jews & Gentiles] have access by one Spirit unto the Father.

   There are a lot of things that a person could believe about the Lord Jesus Christ.  He was a good man.  He was a prophet.  He spoke God's Word.  He condensed the law into two commandments: love God and love your neighbor. . . However, the foundation of our believing lies in the resurrection of Christ, his being seated at the right hand of God, his shedding forth of the holy spirit on Pentecost,  the fullness of Christ in you today!, and our hope for his return to gather us.  These truths regarding Christ are the foundation of our believing.

Ephesians 2:19-22
   Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;
   And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone [foundation stone];
   In whom all the building fitly framed together groweth unto an holy temple in the Lord:
   In whom ye also are builded together for an habitation of God through the Spirit.

   Jesus Christ is the foundation stone.  In the Bible lands a house was built upon a single slab or foundation stone.  Jesus Christ is not just a stone in the building; he is the entire foundation.  He is the foundation of a building of believers that together make a house or habitation of God.  When we believed [Romans 10:9-10] regarding the resurrection of the Lord Jesus Christ we were filled with the holy spirit from God.  We became part of the collective building of believers that is God's dwelling place or temple in our day and time.  This is the foundational truth that we believe regarding Christ.

Romans 16:25
   Now to him that is of power to stablish you according to my [Paul's] gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began.

   That which we believe regarding Jesus Christ and preach to others is to be "according to the revelation of the mystery."  As we continually work the foundational truths regarding that which became available on the day of Pentecost and that which we have in us as a result of the accomplished work of the Lord Jesus Christ, God will "stablish" us.  The word stablish means to set fast.  We are to be founded, set fast, grounded and settled in the foundational truth of the mystery of God revealed to the Apostle Paul and set forth in the Epistles of Romans - Thessalonians.

Colossians 2:6-7
   As ye have therefore received Christ Jesus the Lord, so walk ye in him:
   Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving.

   We are to be rooted in Christ Jesus.  We are to be built upon the foundation of Christ.  We are to be stablished in "the faith."  The word "faith" in the Bible is the word "believing."  When the Bible also adds the article "the" it emphasizes that there is only one right way of believing.  We are to be stablished in "the right way of believing" as we have been taught.  We are not to be always looking for some new thing to teach and believe.  We are to keep coming back to the foundation: Jesus Christ according to the revelation of the mystery.

Colossians 2:8-10
   Beware lest any man spoil [rob] you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.
   For in him dwelleth all the fulness of the Godhead bodily.
   And ye are complete [full] in him, which is the head of all principality and power:

   We are not to be blown about by the philosophies and traditions of men.  We are to be established in the foundation of Christ.  We are to recognize that God dwells in Christ and Christ dwells in us.  All the fullness of God is in Christ and we are filled in him.  It is God in Christ in You!  That is the foundation of Jesus Christ according to the revelation of the mystery.

Ephesians 3:17-19
   That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love,
   May be able to comprehend with all saints what is the breadth, and length, and depth, and height;
   And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God.

   Spiritually we are filled with all the fulness of God.  Now we have to get persuaded in our hearts about it.  We are to be rooted and grounded in the love of Christ that dwells within us.  And with the other believers, with all saints, we can begin to understand the foundational love of Christ that passeth knowledge; and in our minds begin to be filled (as we are spiritually) with all the fullness of God.

Colossians 1:23
   If ye continue in the faith [the right way of believing] grounded and settled, and be not moved away from the hope of the gospel, which ye have heard, and which was preached to every creature which is under heaven; whereof I Paul am made a minister;

   We are to be grounded and settled, planted, in the right way of believing concerning Jesus Christ according to the revelation of the mystery.  Part of that foundational doctrine is our hope for the return of Christ.  As we hold the hope of Christ's return, and do not allow ourselves to be moved away from that hope, we become grounded and settled in the foundation of Christ.

I Corinthians 15:51-52 . . . 58
   Behold, I shew you a mystery; We shall not all sleep [die], but we shall all be changed.
   In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall [absolutely!] sound, and the dead shall be raised incorruptible, and we shall be changed.
   . . . Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord.

   We are to be unmoveable - grounded in the foundation of Jesus Christ according to the revelation of the mystery which includes walking in light of our hope for his return at which time we shall be changed and receive a body like his glorious resurrected body.