3 Beloved,  when I gave all diligence to write unto you of the common salvation, it  was needful for me to write unto you, and exhort you that ye should  earnestly contend for the faith which was once delivered unto the  saints.

4 For  there are certain men crept in unawares, who were before of old  ordained to this condemnation, ungodly men, turning the grace of our God  into lasciviousness, and denying the only Lord God, and our Lord Jesus  Christ.

Jude 1:3-4 KJV

8 Remember that Jesus Christ of the seed of David was raised from the dead according to my gospel:

9 Wherein I suffer trouble, as an evil doer, even unto bonds; but the word of God is not bound.

10 Therefore  I endure all things for the elect's sakes, that they may also obtain  the salvation which is in Christ Jesus with eternal glory.

11 It is a faithful saying: For if we be dead with him, we shall also live with him:

12 If we suffer, we shall also reign with him: if we deny him, he also will deny us:

13 If we believe not, yet he abideth faithful: he cannot deny himself.

14 Of  these things put them in remembrance, charging them before the Lord  that they strive not about words to no profit, but to the subverting of  the hearers.

15 Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.

16 But shun profane and vain babblings: for they will increase unto more ungodliness.

2 Timothy 2:8-16 KJV 

Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand;

2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.

3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;

4 And that he was buried, and that he rose again the third day according to the scriptures:

5 And that he was seen of Cephas, then of the twelve:

6 After  that, he was seen of above five hundred brethren at once; of whom the  greater part remain unto this present, but some are fallen asleep.

7 After that, he was seen of James; then of all the apostles.

8 And last of all he was seen of me also, as of one born out of due time.

9 For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God.

10 But  by the grace of God I am what I am: and his grace which was bestowed  upon me was not in vain; but I laboured more abundantly than they all:  yet not I, but the grace of God which was with me.

11 Therefore whether it were I or they, so we preach, and so ye believed.

12 Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead?

13 But if there be no resurrection of the dead, then is Christ not risen:

14 And if Christ be not risen, then is our preaching vain, and your faith is also vain.

15 Yea,  and we are found false witnesses of God; because we have testified of  God that he raised up Christ: whom he raised not up, if so be that the  dead rise not.

16 For if the dead rise not, then is not Christ raised:

17 And if Christ be not raised, your faith is vain; ye are yet in your sins.

18 Then they also which are fallen asleep in Christ are perished.

1 Corinthians 15:1-18